Fatal system error

Hello,
Im having a serious problem with my laptop. Yesterday it worked fine but later when i rebooted it just keeps rebooting. Ive tried lots of stuff but cant get anywhere. Its now stuck on a blue screen & showig the following messege;

Stop: c000021a {fatal system error}
The windows logon process system process terminated unexpectedly with a status of 0x000012f (0x00000000 0x00000000).
The system has been shut down.

Can i fix this problem?-
I have torn the house apart looking for XP cds, back up cds etc but cant find anything?

Please help!!!!