Has your processor been at 100% utilization lately? If you went to the Task Manager in Windows and looked at your processes tab, you may have noticed a process called msmpeng.exe eating up all your available CPU.
So what is msmpeng.exe and how can you prevent it from slowing your system down? Well, unlike what you may have read elsewhere, it is not spyware or malware. It’s actually quite ironic because it’s associated with Windows Defender, the anti-spyware product from Microsoft.
Unfortunately, this crappy piece of software is already installed on Windows Vista and it also comes with Windows Live One Care. There are two ways to stop msmpeng.exe from using system resources: exclude the Windows Defender directory from scanning or simply turn off Windows Defender.
Exclude directory for scanning
If you would like to keep using Windows Defender, then your only chance of fixing the high processor usage issue is to prevent the Windows Defender directory from being scanned.
Apparently, the service scans it’s self and therefore eats up all the CPU. Open Windows Defender, click on Tools and then Options. Now scroll down to the Advanced Options section:
Now click on the add button under the “Do not scan these files or locations” section. Now type in the path for the Windows Defender directory:
c:\program files\windows defender
Click OK and now make sure to click the Save button. Hopefully this will fix your high CPU usage error with Windows Defender. Also be sure to read my post on how to customize all the options for Windows Defender like what stuff to monitor in real-time, etc.
Turn off Windows Defender
The other option is to simply turn off Windows Defender, which I think is a better idea anyway. There are lots of other spyware programs out there that are much better than Windows Defender.
To turn off Windows Defender, open the program and click on Options. Now go to Administrator options and uncheck the Use Windows Defender box. Make sure to click Save.
![what is msmpeng[5]](http://s.helpdeskgeek.com/wp-content/pictures/2009/03/whatismsmpeng5.png "what is msmpeng[5]")
So that’s it! msmpeng should now no longer be messing up your system. If you’re still having troubles, post a comment here. Enjoy!
Same thing – no Defender running, but I do have MS Security Essentials. I opened it and changed the settings. No more monitoring file & program activity, excluded itself, and the external drives. Will see if that helps.
Windows XP Proffesional service pack 3, Microsoft Security Essentials 2
Excluding maps and processes from MSE were no good (and I bet, not that good considering possible infection of MSE itself)
My problem was residual left overs from an old anti-virus program (Norman Virus Control v5.99).
There was no trace to be found of the old program, no file, no registery info.
Only hint was the security centre of windows which told me I had more then one anti-virus installed.
Problem was, it didn't tell me which it was, just saying 'more then one, and at least 1 was updated and functioning'.
Had to uninstall MSE to learn from the security centre what other program was 'installed', which was Norman.
Had to reinstall Norman and 'correctly uninstall it via the official uninstall file, restart, reinstall MSE and it was done. :-D
For Windows XP SP3 with Microsoft Security Essentials do this (thanks to todd94590)
1. Open MSE, go to Settings
2. Add "c:program filesMicrosoft Security Client" and "c:program filesMicrosoft Security ClientAntimalware" to Excluded files and locations
3. Add "c:program filesMicrosoft Security ClientAntimalwareMsMpEng.exe" to excluded processes
Be sure to click Save Changes! Hope it works for ya.
In addition to my previous post see also this: http://answers.microsoft.com/en-us/protect/forum/…
Running a full scan solved my problems entirely