Windows 10: Windows Defender unable to complete a full scan of the disk / shuts down computer / weird

Hi,

Every now and then I like to run a full scan of all the drives in my computer (Windows 10). Lately I am unable to complete this task. The symptoms are a little weird. When I kick off either a full or custom scan I see the CPU utilization ramp up ultimately to the point (after a few minutes) where all 8 cores are running at 100%. I hear the CPU fan accelerate. After a short time the computer shuts itself off. Now, I am guessing that I have a BIOS setting somewhere that detects the CPU temperature and shuts everything off to keep things from melting, and I suppose I could turn this off. However, this is new behavior for the machine, and I would prefer not to turn off the "please don't melt my CPU" bios setting. I am unable to set the affinity for MsMpEng.exe (Access is denied). I have also tried to set the group policy for Computer Configuration --> Administrative Templates --> Windows Components --> Windows Defender Antivirus --> Scan --> Specify the maximum percentage of CPU utilization during a scan to 20% but this has no effect. I am able to fully scan all disks with Malwarebytes without a problem. I ran sfc /scannow -- which recently reported and repaired some file permissions errors, but otherwise the machine works as always. Has anyone seen something like this? Seems like if I could just set the affinity to only use 1 or 2 cores I would be all set, but so far I've had no success getting Task Manager to allow me to do this. Is there a way to force the affinity somewhere else?

Thanks in advance,

Tom

:)

 

Windows Defender not completing scans

Hi,

Thank you for posting your query on Microsoft Community.

As per the description, I understand that you are facing issues using Windows Defender.

I would suggest you to go through the below methods:

Method 1: Set Windows Defender to Automatic

You can set the Windows Defender service to Automatic, Disabled or Manual. Setting it to automatic might solve the problem. Follow these steps:

• 
  Click Start > type services in the Search box > click Services in the Programs list.
  
  2. Search for Windows defender.
  
  3. Double-click Windows Defender, and click Automatic in the start-up box > click OK.
  
• 
  

Method 2: Run SFC scan, it will check, if there is any kind of corruption on the operating system.

• 
  Press WIN+X.
  
• 
  Click on command prompt with admin.
  
• 
  Type sfc /scannow and press enter.
  
• 
  Reboot the computer once finished.
  

Method 3: Try the below link:

https://support.microsoft.com/en-us/kb/931849

Hope this information helps. Please let us know if you need any other assistance with Windows in future. We will be happy to assist you.

 

Windows 10 is unable to complete shut down

We suggest doing these troubleshooting steps below:

Method 1. Hard Reset

• Shut down your computer.
• Remove the cable and wires connected to your computer.
• Press the Power button for 10 seconds to completely drain your device.
• Check if there's any changes.

Method 2. Shutdown trick.

• Press Windows key.
  
• Press and hold Shift.
• Click the Power icon.
• Select and click Shutdown.

Let us know the outcome.

 

Defender won't complete a scan

Once again I draw your attention to the link I gave earlier:

Particularly these words:

Scan could not complete
If scans are taking too long or appear to be progressing very slowly, consider the following solutions:

• Ensure you have sufficient disk space
• Run focused scans while your PC is idle

Ensure you have sufficient disk space
Windows Defender Antivirus requires disk space to remove and quarantine malware files. It might be prevented from completely removing a threat if there isn't enough space on your PC, particularly on your system drive (commonly drive C). See the following
to help free up space:

• Free up drive space in Windows 10
• Tips to free up drive space on your PC (Windows 8.1, Windows 7)

After you've freed up some space, update and then
run a scan again.

Speed up scans
In general, full scans can take a long time if you have a large disk with lots of files. Large files, especially archives such as ZIP files, take longer to scan.

Quick scans complete much faster than full scans and are
designed to check areas that most often harbor threats. To speed up scans, close other applications and run scans while your computer is idle. Advanced users can also

try running scans with special switches.

Windows Defender Antivirus encounters errors
If Windows Defender Antivirus continually encounters errors during scans or during malware removal, try the following solutions:

• If Windows Defender Antivirus encounters an error, we recommend you provide feedback to Microsoft, so we can deliver fixes as fast as possible. By default, Windows automatically collects error information, but
  
  describing the error on the Feedback Hub app can help us address the error more efficiently.
• To resolve errors immediately, advanced users can
  look up the error code to check for possible causes and solutions.
• Run Windows Update to apply any fixes and ensure you have the latest components.
• If Windows Defender Antivirus continually encounters errors during updates,
  try installing the latest protection updates manually.