windows xp rebooting at logon

[Guest]

when i get to logon screen in windows xp home with sp2 i type in my username
and password hit ok then i get bsod and the message stop c000021a fatal
system error the windows logon process terminated unexpextedly with a status
of 0x0000005 (0x00000000 0x00000000) its the exact same in safe mode i can f8
to the options but when i logon it restarts any help?

 

[Mark L. Ferguson]

0xc000021a STOP error,where the ntoskrnl.exe or ntdll.dll files were not
replaced, Boot to Recovery Console, check version, date and time of
ntoskrnl.exe and ntdll.dll. expand them from the SP2 install source,
available in %windir%\servicepackfiles folder