If you're using an SSD, Superfetch is off by default as it doesn't make sense in an SSD system.
If you're using Server 2008 R2, Superfetch is off by default.
If you're using Windows 7 on a conventional hard drive:
Run "net stop fileinfo", and delete the following three files under... AgGlFaultHistory.db AgGlFgAppHistory.db AgGlGlobalHistory.db (all under C:\Windows\Prefetch)
"SC Start SysMain" will get it going again.