1st thing I would do is try the "sfc /scannow" from the run menu that was already recommended, but make sure the XP cd is in your master cd-rom drive. If you want to use the recovery console, put the xp cd in the master cd-rom drive, reboot, watch the screen & when it says "press any key to boot from cd..." press a key. Let it load, then instead of choosing repair from the main menu, choose the first option to install XP. When it shows that you already have XP installed - press R and start repairs from there.
actually their is a procedure of order for repairing xp from old ms themselves.but you can choose the order depending on the situation. I always do 1 then 6
2.restore a previous point of the system
3.boot to command options F8 and choose restore last good configuration
4. device driver rollback
6. norton ghost backup/or other as we all have a backup