Doing a repair install of XP often fixes system problems. But don't forget, when you do the repair, you may need the system driver disks, your printer install disk, or other software. A lot of times you can get drivers from the manufacturer website.
Don't do a repair until you have backed up your personal files to CD, DVD, or an online backup service. There is always a chance that something could go wrong, and you could loose your personal files.