A few suggestions off the top of my noggin', depending upon where your system's head is ...
On start up see if you can get into safe mode to check things out. While there see if you can unload whatever it was that you loaded prior to this "problem" occurring. While in safe mode, be sure your XP disk is in its original drive bay and then open the cmd window and do the sfc /scannow command, the defrag and do a disk check on restarting things. Start> run> cmd then hit enter...
Do you have a system restore file, so that upon start up you can hit, what is it? f9 I think, anyway its at the bottom of the DOS screen where the function keys are noted along the bottom of the screen. The darn thing goes so fast that sometimes you have to start up a few time to read them. Once read put some sort of marker on the key board and then you won't have to worry about it again.
Do you have the setup floppie disks from MS for XP...there are six of them, they will get you past the boot stage to a fresh Windows, keep your original XP disk in the proper drive bay.
Don't forget to defrag and disk check on next startup...
Edited by b1caez01, 01 September 2006 - 10:22 PM.