each and every time I go home I have to deal with computer issues with my parents... so I got in the habit of backing up their files and just completely restoring the computer EVERY time I go home... even if it's not having issues. just safer that way
I do that on my computers too actually... about once a year, on a long weekend... (in winter of course) i'll wipe out my computer and start over from a Ghost image. greatly reduces the amount of problems I've had.