Man I just went thru this same problem with my friends SEMPRON 2600. It just wouldn't handle the Fruity, Acid, or Cubase. System would just always crap out.

Once he switched to a 64bit chip that was no longer a problem. Even the old Athalons seem to handle the applications better than the semprons do. Although maybe this was isolated, but it sounds like you're having the exact same issue.