Sempre há a solução manual…

https://support.avast.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=580
http://support.microsoft.com/mats/windows_security_diagnostic/
http://forum.avast.com/index.php?topic=23457.msg193534#msg193534

Run command line as admin:
net stop winmgmt
del C:\WINDOWS\system32\wbem\Repository
net start winmgmt

winmgmt /verifyrepository
winmgmt /salvagerepository