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msmpeng.exe causes CPU spikes that happen every 15 mins or so, and it has finally got to me. As far as I can remember, I started facing this after installing MS Security Essentials on my Windows 7 Ultimate PC. I use genuine Windows, update it when updates are available and do not have any other anti-virus installed (I clean installed Avira using Revo before installing security essentials)

I have been doing a lot of research on this trying to figure out ways to stop this. I've tried things mentioned from 1st Byte, but nothing has worked.

I've also added more exclusions, disabled behavior monitoring, limited CPU usage during quick scan which happens only once a week.. nothing seems to work. Every while or so, the computer will freeze for a minute or so, and when I can access task manager, I see msmpeng.exe at the top and then coming down slowly.

The last resort obviously would be going back to avira or avast or whatever, I'd prefer to keep using Security Essentials.

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I've had the same issues with MS-SE in the past. It was really bad, so I uninstalled it. Installed AVG Free, the UI on that crashed almost immediately, so I switched back to MS-SE. It seems better now (for no apparent reason) but my system will still "freeze" for about 1/2 second very 20-30 minutes. My settings are default, I haven't customized it at all. – Melikoth Nov 30 '11 at 12:54
Some things to try. First make sure that the built in Windows Defender is disabled. Secondly, try running the Avira uninstall registry cleaner ( Lastly, I suggest using Process Monitor ( to determine if it is repeatedly scanning files, and if so then add the path to the list of exclusions. – James Nov 30 '11 at 13:24

No, you can not stop MSE. Only thing you can do is uninstall it. If you have another antivirus running you can disable real-time protection, but that's about it. Sad.

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