Did you have Norton System works on this PC?
http://support.microsoft.com/?kbid=316503&sd=RMVP
This may also help:
http://support.microsoft.com/default...b;en-us;156669
Are you able to get into SAFE MODE or select LAST KNOWN GOOD CONFIGURATION
Tap the F8 key at bootup and see if you can get into SAFE MODE.
Bill