Virus Attack

Can anyone identify which virus this may be.
Initial symptoms. Browser (IE7) froze. Then everything else did. Could shut down with task manager.
Rebooted. Desktop appears then resets continually several times, finally disappearing altogether. Shutdown is only possible via Task Manager, nothing suspicious appears to be running under task manager. Shuts down with BSD!
Safe mode will boot, but likewise GUI continually bounces making it impossible to run anything. I did manage to select windows restore but the only one available was the one after the virus installed itself. Impossible to select any other.
System is XP Pro, Intel board with raid0 and 2×3.4 Xeons, Antivirus Symantec Corp 10 latest definitions