My laptop keeps restarting when it boots up

I have an Acer laptop with windows xp and i got a virus on it. I ran my antivirus software and it deleted some stuff and i remember one of theme being a HKEY thing then it advised me to restart. I did and everything boots normally until its about to ask me to log in then it gives me the blue screen saying:

STOP: c000021a {Fatal System Error}
The windows logon process system process terminated unexpectedly with a status of 0xc0000135 (0x00000000 0x00000000).
The system has been shut down.

I tried going into safe mode and a bunch if other stuff on the f8 menu but nothing works. I cant logon or access anything. Please help!!!