You can find a partial explanation of the error message here.
http://aumha.org/a/stop.htm
0xC000021A: STATUS_SYSTEM_PROCESS_TERMINATED
"This occurs when Windows switches into kernel mode and a user-mode subsystem,
such as Winlogon or the Client Server Runtime Subsystem (CSRSS), is compromised.
Security can no longer be guaranteed. Because Win XP can’t run without Winlogon
or CSRSS, this is one of the few situations where the failure of a user-mode
service can cause the system to stop responding. This Stop message also can
occur as a result of malware infestation or when the computer is restarted
after a system administrator has modified permissions so that the SYSTEM
account no longer has adequate permissions to access system files and folders.
# GoBack Causes a Stop Error C000021a {KB 316503} Win XP
# Internet Explorer Maintenance Policies May Cause an
Access Violation in Winlogon {KB 318666} Win XP Pro "
HTH,
Paul