If you are looking for error detection on cd's and Dvd's then
CDCheck does the trick for you
"CDCheck is a utility for the prevention, detection and recovery of damaged files on CD-ROMs with an emphasis on error detection. With CDCheck you can check your CDs and discover which files are corrupted. CDCheck does support DVDs "
It is free for personal use.
You can download it from here
If you are looking for Registry Errors then
"RegScrubXP" Is free software for windows 2000/xp
It safely cleans junk out of the Windows 2000/XP system registry. All changes made to the registry are fully restorable to it's original condition.
It is free for personal use.
You can download RegScrubXP from here