Virus Conflicts with XP

Hello everyone!

A friend of mine is running WinXP and had Virucide 2001 on her machine. She wasn’t satisfied with her the program so I gave her a fresh copy of Norton Antivirus 2002. She uninstalled the Virucide, then installed Norton Antivirus. Her computer now will boot completely up to the XP desktop, but like 5-10 seconds later it will give the “blue screen” and go through a physical memory dump 0-100 then restart. I tried to go into safe mode to uninstall Norton or even just take out all of Virucide 2001 registries in REGEDIT, but it won’t let me do either in Safe Mode. Any suggestion other than reformatting the disk??? Please help!