Stop : C000021a Fatal system error

My sons comp is showing this after replacing the processor, and we can't even get into safe mode or the recovery console, has anyone else experienced this problem, or even got a solution ?

STOP: c000021a {Fatal System Error}
The Windows Logon Process system process terminated unexpectedly with a status of 0xc0000135 (0x00000000 0x0000000)
The system has been shutdown.

Please Help !

P.S I know i'm an established member BC but was just a little unsure as to where to post this thread, so i'll apologise now if this is in the wrong dept !
Thankyou for any help in Advance !

Edited by doinmeedin, 26 October 2009 - 04:56 AM.

System manufacturer and model?

The error reported...arises from many different causes. You can verify that by using Google for the designated error.

You will note that several persons suggest using a registry cleaner to "fix" the problems noted. I suggest that this is unwise advice and it's impossible since you cannot boot into Windows.

Louis