I'm unable to get my computer past the Windows XP screen without a blue screen, keeps rebooting.
I was able to get to the Windows Advanced Options Menue and was able to "Disable automatic restart on system failure" to get the entire error message.
Stop: c000021a {Fatal System Error}
The Session Manager Initialization system process terminated unexpectedly with a status of 0xc000026c (0x00000000 0x00000000).
The system has been shut down.
Twice I was able to get to "Safe Mode", words ran across the screen like they normally will do when in "Safe Mode", but both times the computer restarted again.
I tried running a repair multiple times with a borrowed Windows XP disc, each time after the repair it said that the system had errors but had been repaired, but the problem continues, computer just keeps rebooting, shutting down with the error message again in a loop. Hopefully this helps.