I have had this problem since first installing Windows 7 x64 for over a year. After reading a kazillion threads, I came across this one.

Shortly after boot, superfetch (sysmain.dll) would try to load and crash, together with about 6-8 other services. Aero would also crash. No BSOD but it was a big pain!!!!

Checked the two registry settings (EnableSuperfetch' & 'EnablePrefetcher) and they were set to 3. I first stopped the Superfetch service (made sure that it was set to automatic), deleted everything from c:\windows\prefetch, changed both registry settings to 1 and rebooted. Problem solved!!!!!

The reason I am posting is because it may help others get rid of this hideous error.

Many thanks Ezio. The liberation of Roma has begun.

HKLM\System\CurrentControlSet\Control\Session Manager\Memory

Both 'EnableSuperfetch' & 'EnablePrefetcher' need to be set to a value of 1.

System Services Solved - Windows 7 Help Forums