I would diss hardware issues in this. Even on my athlon 2000+ system 1/2 gb of ram, occasionally something funky happens. Once all of my sound files became corrupted (or at least the important ones). Once every couple of months it will start to warp and lag and stutter, a scandisk and a defrag always fixs it. I know is sounds like a bad drive but this is the third drive with identical problems (*fresh installs and new oses even).
ALways remember bill gates is an arsewipe and his oses blow chunks. but of course its all we have...