This error is widely reported on laptops that never get a cleaning of the vents or are Pentium 4 based. Details like that do help.
my laptop shut itself down today and would not let me back on windows. i get the error message "c000021a fatal system error. windows logon process terminated unexpectedly with a status of 0x0000420 (ox00000000 0x00000000). the system has been shut down."
it kept auto restarting. i tried going in to safe mode and safe mode with networking, and it wouldn't let me in, kept shutting me down.
then after numerous tries i was able to logon normally and system restored and was able to logon normal the next couple reboots, but it did not fix the problem i am again getting the error message and getting shut down trying to get to safe modes. then after numerous tries i got on windows normally again. can someone help?