Will it boot into "Safe Mode"???

Turn on the PC, while tapping the "F8" button (on the top of the keyboard). Then use the up and down arroows on the keyboard to select "Safe Mode"

Hit "Enter"

Try this link if you can boot into safe mode

If not, try HERE

If nothing else, a repair or fresh install of XP may be required. A fresh install will erase all of your data.