If it boots in safe mode while not booting successfully otherwise...driver corruption would be my guess.
Bear in mind that there are all sorts of drivers operative...not just hardware, but programs such as firewall, AV, image-editors, music-editors/players, etc...all have ddrivers.
"Corruption" is just computerese for "damaged."
System manufacturer and model?
Do you have a MS XP install CD?
Can you try Last Known Good Configuration?http://support.microsoft.com/kb/307852