Windows 10: How to fix Microsoft virus defender has stopped working. Restart it now + High CPU usage...

Since updating my pc, nothing has been working, and I've been getting high disk and CPU usage, because of these errors.

> Microsoft virus defender has stopped working. Restart it now, also just read that it has been caused by the newest update, but I don't have the chance to update my computer to the last back up, since I don't do those, and I do too much stuff every, which will cause everything to get lost, no thanks.


My Opera Gx and Opera has been starting to freeze after opening them, for about 30 seconds, and that's probably caused by the virus protection too.


I used malware bytes 2 days ago, and deleted every virus my computer had, and there was only 1, which now is gone. I haven't downloaded any other software from that day, other than the windows update.

:)

 

Windows 10 High CPU usage Fix

Hi i'm writing here to post an answer to the Windows 10 High CPU issue that i found and also ask the Microsoft Team why does this occur so i can understand it.

So to the answer; my CPU usage all of the sudden became high over the last few weeks, i'd tried to trouble shoot as others and Microsoft had suggested, though nothing worked. Microsoft has suggested to create a new account and transfer files which also proved
fruitless after transferring files as explorer.exe again consumed high CPU usage. It was just luck that i stumbled across the solution in one of these threads that linked to an answer from 2011.

Firstly i just want to state that i did download process explorer and it had revealed it was explorer.exe causing high CPU usage and not a .dll file.

The solution:

Broken icons on desktop. That's it. After reading The Solution i found i had 3 desktop files with no
icons at all. I deleted these three files (two shortcuts, one PDF) and instantly the CPU usage by explorer.exe dropped from a constant 38-40% down to 0.2%

I was wondering if someone or Microsoft might be able to clarify what causes this to actually happen?

Thank you

 

Windows 10 Defender Full Virus Scan- CPU Usage 100%

High CPU usage has been encountered before: this thread (older) refers to dealing with a corrupt database file, but it's a bit long.
High CPU usage from Windows Defender

There are other such threads if you search for (e.g.)
Defender high cpu usage





In the past, sometimes it's proved necessary to exclude a folder:
High CPU usage from Windows Defender
(same thread)

 

Windows Defender - high CPU and disk usage

Thank you very much for your quick response. I've taken all steps you suggested. This is the outcome:

• Add a process exclusion
  
  Unfortunately, this didn't work. I added both a path and a process exclusion now.The task scheduler for
• Defender looks like this for me:
  
  
  
  

• It seems no Defender tasks have run since June 30th, yet the process continues to hog the CPU
• I re-ran SFC /scannow. SFC could not find any integrity violations
• I tried disabling behaviour monitoring. The setting did not persist across a reboot, and turning it off did not make a difference while my system was still running.
  
  
  This was the output for Powershell:
  
  

PS C:\Windows\system32> Set-MpPreference -DisableBehaviorMonitoring $True

PS C:\Windows\system32> Get-MpPreference | findstr "Behavior"

DisableBehaviorMonitoring : True

PS C:\Windows\system32>

• Scanning for viruses and leftover antivirus software. This was interesting (yet unfruitful):
  
  Neither Kaspersky nor Emisoft could find any threats. MalwareBytes did find 5 executables in my temp folder, although Virustotal.com reported no danger for the files. This could mean it's a false positive, but I removed all traces of them anyway.
  
  It also found two installers (PUPs) for a Spigot toolbar, I removed those as well. They probably came with some free software package, I try to prevent installing toolbars.
• In installed AVG Anti Virus (the free version). When I rebooted after the installation, Defender was still running and taking up 25-30% of my CPU. I disabled Defender using the Group Policy editor and the service finally stopped.

AVG works for me, but like most free anti virus programs it's full of ads and "free offers" and fishy SSL/TLS interception ("web protection").

I'd like to keep using Windows Defender because it's neatly integrated into Windows 10, doesn't take a lot of resources and doesn't show annoying ads.

I hope anyone can suggest another way to fix this weird Windows Defender problem.