Security experts have concluded that PC Cleaner is a system optimizer. The so-called “system optimizers” intentionally use false positives in scan results to suggest computers need to buy a full version of the product before the problems can be solved.
The Windows Registry is a database of settings for all software, hardware, and the user preferences on a computer for how the operating system handles the applications and hardware. Standard Windows users are not required to access or edit the registry, though they may sometimes enter it to make modifications.
Some third-party programs—that claim to be “registry optimizers,” “registry cleaners,” so forth—may suggest the Windows registry needs cleaning; however, running these programs can lead to serious issues and may damage the Windows registry. If you run a tool that says it cleans the registry and damage occurs, it may require you to reinstall the operating system.
If the Windows registry does get damaged, it can result in various forms of system instability: longer startup and shutdown times, random crashes or hangs, and poor app functionality. Reinstalling the operating system is often the only way to solve these problems.
Many times people think their computers are too old to work properly when in fact they have run a so-called “registry cleaner” which has damaged the registry, and that is the reason for the slow operating system. Wasting time while waiting for the computer to complete tasks is a huge issue that arises from a damaged registry, but so too is the potential data loss that may occur if you are forced to reinstall the operating system due to constant computer crashes.
The following tutorial demonstrates how to remove the malware from your computer.
Method One: How to Remove PC Cleaner System Optimizer Using Microsoft Defender in Windows 10
Windows offers ways to remove malware using Microsoft Defender. Here is how:
See also: How to Use Malicious Software Removal Tool in Windows 10
Part One: How to Enable or Disable Microsoft Defender PUA Protection in Windows 10
When removing Potentially Unwanted Programs from your computer with the default Microsoft Defender antivirus, you should enable PUP protection first. Here is how to do that:
Option One: How to Enable or Disable Microsoft Defender PUP Protection in Windows PowerShell
1. Open an elevated Windows PowerShell. See this tutorial to read all the different ways in which you can open the elevated version of the Windows PowerShell: How to Open Elevated Windows PowerShell in Windows 10
2. If you are prompted by User Account Control, click on the Yes button.
3. Type one of the following commands into the Windows PowerShell window, depending on what you want to achieve, and then press the Enter key on your keyboard to execute it:
To Enable Microsoft Defender PUA Protection:
Set-MpPreference -PUAProtection 1
or
Set-MpPreference -PUAProtection Enabled
To Disable Microsoft Defender PUA Protection (Default):
Set-MpPreference -PUAProtection 0
or
Set-MpPreference -PUAProtection Disabled
Audit Mode – detects PUPs, but does not block them:
Set-MpPreference -PUAProtection 2
or
Set-MpPreference -PUAProtection AuditMode
4. Restart the computer before attempting to run a new Microsoft Defender antivirus scan that searched for extra PUPs.
You can now close the Windows PowerShell window and continue using your computer if you like.
Option Two: How to Enable or Disable Microsoft Defender PUA Protection in Local Group Policy Editor
Notes:
- You can only use this option from the Local Group Policy Editor starting from Windows 10 version 1809.
- The Local Group Policy Editor is only available in Pro, Enterprise, and Education editions of Windows 10.
- Though Microsoft changed the name Windows Defender to Microsoft Defender in Windows 10 version 1909, as of yet, the Local Group Policy Editor has not been updated to reflect this change. Should there come a time when the following path no longer works, try exchanging Windows Defender for Microsoft Defender in the Local Group Policy Editor where applicable.
1. Open the Local Group Policy Editor (gpedit.msc). See this tutorial to read all the different ways in which you can open the Local Group Policy Editor: How to Open Local Group Policy Editor in Windows 10
2. Using the Local Group Policy Editor’s left pane, navigate through to the following location:
Computer Configuration\Administrative Templates\Windows Components\Windows Defender Antivirus
3. With Windows Defender Antivirus selected, click on Configure detection for potentially unwanted applications from the right pane. (click to enlarge screenshot below)
4. From the Configure detection for potentially unwanted applications policy, select either Not Configured (to turn off Windows Defender PUP protection), Enabled (to turn on Windows Defender PUP protection), or Disabled (to turn off Windows Defender PUP protection). (click to enlarge screenshot below)
Note: If selecting Enabled, a drop-down menu appears in the Options window that offers additional options to configure the group policy if you like. For example, from the drop-down menu, you can select Blocked which means the Configure detection for potentially unwanted applications policy will be enabled, and the potentially unwanted programs will be blocked from being downloaded onto your computer. It is suitable for most people to select Blocked from the drop-down menu in the Options window to stop PUPs getting onto your computer in future.
You can now close the Local Group Policy Editor and continue using your computer if you like.
Part Two: How to Manually Scan Files, Folders, and Drives with Microsoft Defender in Windows 10
Windows 10 provides the latest antivirus protection with Windows Security. Your device will be actively protected from the moment you start Windows 10. Windows Security continually scans for malware (all types of malicious software), viruses, and security threats. In addition to this real-time protection, updates are downloaded automatically to help keep your device safe and protected from threats.
Some features differ if you are running Windows 10 in S mode. Because this mode is streamlined for tighter security, the Virus & threat protection area has fewer options. However, that does not mean it is less secure—the built-in security of this mode automatically prevents viruses and other threats from running on your device, and you will receive security updates automatically.
Microsoft Defender automatically scans your system periodically, so it should pick up and remove any malware on your computer by itself over time. If you need a quick solution, Microsoft Defender also allows for manual scans so that you can scan any location on the operating system immediately.
Note: The Microsoft Defender antivirus application shown below comes out of the box on all versions of Windows 10, the latest version of Windows operating system. If you are running an older version of Windows, such as Windows 7, then you can skip to one of the next parts that shows you how to install a third-party antimalware application instead.
Option One: How to Scan with Microsoft Defender Using Context Menu
Here is how you can run an antivirus scan with the built-in Microsoft Defender antivirus program from the context menu of a file or folder:
Notes:
- The Windows Security is available in all versions of Windows 10 after version 1703.
- While Microsoft has changed the name from Windows Defender to Microsoft Defender as of Windows 10 version 1909, most locations around Windows, including the context menu via File Explorer, still list the older Windows Defender name. Should there come a time when the following path no longer works, try clicking on Scan with Microsoft Defender… instead of Scan with Windows Defender… from the context menu instead.
1. From File Explorer, select the drive, folder, or file that you suspect may contain the potential malicious program.
2. Right-click on Scan with Windows Defender from the context menu. (click to enlarge screenshot below)

3. When the scan completes, Windows Security will open and show you the results. The total time for the scan to complete will vary. Scanning drives will take the longest, while scanning individual files the quickest. (click to enlarge screenshot below)
Notes:
-
- The Windows Security application used to be called the Windows Defender Security Center in previous versions of Windows 10. All the settings within the app remained the same after the name change.
- Starting with Windows 10 version 1803, the app has two new areas: Account protection and Device security.

a. If there are no threats found, Windows Security will let you know as much in the same region where it previously show you the scan was underway. (click to enlarge screenshot below)
b. If there are threats found, however, it will let you know there are threats found, as well as the threat names and location in the same area. (click to enlarge screenshot below)
4. To remove any threats found, click on the Start actions button. (click to enlarge screenshots below)
Note: Clicking on Start actions will result in Windows Security removing the threat immediately.

You can now close the Windows Security app and continue using your computer if you like.
Option Two: Scan with Microsoft Defender in Windows Security
Here is how you can run an antivirus scan with the built-in Microsoft Defender antivirus program from the Windows Security app:
1. Open Windows Security. See this tutorial to read all the different ways in which you can open Windows Security in Windows 10: How to Open Windows Security in Windows 10
2. Click on the Virus & threat protection icon in Windows Security’s Security at a glance page. (click to enlarge screenshot below)
3. Do step 4, step 5, step 6, or step 7 depending on what it is that you would like to do.
4. To Run a Quick Scan with Microsoft Defender
a. Click on the Scan now button. (click to enlarge screenshot below)
5. To Run a Full Scan with Microsoft Defender
a. Select Full scan and then click on the Scan now button. (click to enlarge screenshot below)
6. To Run a Custom Scan with Microsoft Defender
a. Select Custom scan and then click on the Scan now button. (click to enlarge screenshot below)
7. To Run an Offline Scan with Microsoft Defender
a. Select Windows Defender Offline scan and then click on the Scan now button. (click to enlarge screenshot below)
8. Select the file, folder, or drive that you want to scan and then click Select Folder. (click to enlarge screenshot below)
9. Microsoft Defender starts scanning the option that you chose. (click to enlarge screenshot below)
10. When the scan completes, you get the results in numbers. (click to enlarge screenshot below)
11. If there are threats found, however, it will let you know there are threats found, as well as the threat names and location in the same area. (click to enlarge screenshot below)

12. To remove any threats found, click on the Start actions button. (click to enlarge screenshots below)
Note: Clicking on Start actions will result in Windows Security removing the threat immediately.

You can now close the Windows Security app and continue using your computer if you like.
Option Three: How to Scan with Microsoft Defender from Windows PowerShell
Here is how you can run an antivirus scan with Microsoft Defender from the Windows PowerShell:
1. Open the Windows PowerShell. See this tutorial to read all the different ways in which you can open the Windows PowerShell application in Windows 10: How to Open Windows PowerShell in Windows 10
2. Type the command below that best suits your needs and then press the Enter key on your keyboard to execute it.
Update and Quick scan:
Update-MpSignature; Start-MpScan -ScanType QuickScan
Quick scan:
Start-MpScan -ScanType QuickScan
Full scan:
Start-MpScan -ScanType FullScan
You can now close the Windows PowerShell window and continue using your computer if you like.
Option Four: How to Scan with Microsoft Defender from Command Prompt
Here is how you can run an antivirus scan with Microsoft Defender from the command line:
Note: Though Windows Defender has been renamed to Microsoft Defender, Microsoft has not yet updated the commands to reflect this change. Should there come a time when the following commands no longer work, try exchanging Windows Defender for Microsoft Defender in the commands where applicable.
1. Open the Command Prompt. See this tutorial to read all the different ways in which you can open the Command Prompt application in Windows 10: How to Open Command Prompt in Windows 10
2. Type the command below that best suits your needs and then press the Enter key on your keyboard to execute it. (click to enlarge screenshot below)
Update and Quick scan:
"%ProgramFiles%\Windows Defender\MpCmdRun.exe" -SignatureUpdate & "%ProgramFiles%\Windows Defender\MpCmdRun.exe" -Scan -ScanType 1
Quick scan:
"%ProgramFiles%\Windows Defender\MpCmdRun.exe" -Scan -ScanType 1
Full scan:
"%ProgramFiles%\Windows Defender\MpCmdRun.exe" -Scan -ScanType 2
You can now close the Command Prompt window and continue using your computer if you like.
Method Two: How to Remove PC Cleaner System Optimizer Using Malwarebytes
If scanning with the Windows Security antimalware protection doesn’t remove the PC Cleaner system optimizer, you can try installing third-party antimalware tools, such as Malwarebytes, and see if that removes the fake system optimizer instead. You can also use an antimalware program such as Malwarebytes to remove the extensions and all other related files remaining on your computer, so you don’t have to do any of it manually.
Note: Malwarebytes also has an application for smartphones that run on Android and iOS.
1. Download the Malwarebytes for Windows from the Malwarebytes website.
2. If prompted by your web browser with a message that says “This type of file can harm your computer. Do you want to keep the executable (.exe) file anyway?,” click on the Keep button.
3. If you are prompted by User Account Control asking “Do you want to allow this app to make changes to your device,” click on the Yes button.
4. Click on the Scan Now button to begin scanning the computer for malware and other potentially unwanted programs. (click to enlarge screenshot below)
5. Wait for the scan to complete. (click to enlarge screenshot below)
6. Select all of the malware and potentially unwanted programs that you want to be removed from the computer and then click on the Quarantine Selected button. (click to enlarge screenshot below)
7. You may get a message from Malwarebytes letting you know that all selected items have been removed successfully, but the computer must be restarted before the removal process can be completed. Select the Yes button to reboot your computer now. (click to enlarge screenshot below)
8. Upon signing back in to your computer, the Malwarebytes interface will open and let you know that the scan and quarantine are complete. (click to enlarge screenshot below)
Note: You can also export the scan results by clicking on Export summary from the main Malwarebytes results page and then clicking on the Export button from the scan report. (click to enlarge screenshot below)
You can now close the Malwarebytes interface and continue using your computer if you like.
That’s all.
May 28, 2019 @ 10:59
I know a lot of people say that you don’t need any other antivirus apart from Windows Defender that comes preinstalled with Windows 10, but the more I get to know Microsoft the more I’m not so sure.
For starters, I was always a bit skeptical of Windows Defender. When I first made the switch from third-party programs to Windows Defender, I took notice of the scan result differences, and there were plenty. Windows Defender didn’t pick up as many potential threats as the third-party.
OK, maybe the third-party is fluffing their stats and are no different than a system optimizer. That was enough to get me to start using Windows Defender and assume it knew best.
But I constantly have issues with Windows still, even after all the complaints they get. I read one of the employees say that they only have so many resources they can throw at a problem. In other words, they hear the complaints, but they’re short staffed.
Now if you apply that knowledge onto security, what is going to be better: a short-staffed Microsoft team or a dedicated team of antivirus professional working extremely hard to create enough money for themselves to survive. I would argue the latter has a really good chance of being ahead of the game. Yes, Windows is a big company obviously, but only a fraction of their understaffed resources would be thrown at security. And who knows if they’re even as good as these other experts who manage to create their own tools from scratch.
The one obvious advantage Windows Defender had was that is ran much quieter and lighter in the background. Every free third-party tool seemed heavy — I don’t want to hear the fan or be able to see my hardware is being worked by the antivirus software; it seems unnecessary, always has. And Microsoft has proved it could be better when they created an antivirus that you never detect. Even the paid versions I’ve tried, while better, still seem too heavy on an operating system. When you sit in front of a computer all day, you don’t want to be aware of the computer’s components; it needs to be one with the desk.
Yesterday, however, I trialed a new antivirus called G-data, and like computers, it seems antivirus programs have gotten better over the last decade. A lot better. I don’t notice it when it’s running scans or any other time. For now, I’ve decided to go back to third-party antivirus. I realized a problem I had created in my original thinking. If a program isn’t known to be malware, or anything of the sort, then the threats it is showing you are likely to be true. That only leaves one option for Microsoft, if they are hiding threats: they don’t want users to see how many threats there really are. And well, that doesn’t, in any way, twist my arm to use Microsoft’s security.
That being said, I’m not sure Microsoft really cares too much about third-party tools of this sort. There are many tools out there that Microsoft likes, and some niches that Microsoft leaves to third-parties altogether, like backing up.