My computer suddenly started restarting today. It functioned perfectly yesterday. As far as I know, there have been no updates/patches/etc. to my machine.
Most of the time, the machine will make it past the startup Widows splash and will start loading the desktop when it will restart. Sometimes the computer restarts right near the end of the Windows splash section.
Occasionally I can get the computer to start up in safe mode, but there are times when the computer hangs on the login screen (before the user names appear) or will restart. As far as I can tell, once the computer is up in safe mode, it is stable.
When I turn off the auto-restart, I see a BSOD with the error #c000021a. Help would be welcome.
You might try reading this from Microsoft. Personally I would try using one DIMM RAM in slot 1 and see if the system boots to desktop.. Use a DIMM other than the one in the first slot currently. If after trying different RAM combinations doesnt work, a repair install of XP may might be tried by booting to the installation CD if possible. Beyond that if a hardware problem has occured, spare parts would be needed to test further.
I'm about 99% positive that it is not a hardware issue. It seems that following the logic of the link you posted that there is some corruption of the winlogon process. I've looked through regedit for a Gina dll value, but there doesn't appear to be any. Correct me if I'm wrong, but doesn't this mean that the default msgina.dll file is being used? Should I just proceed with a windows repair? Would that solve this problem? I can't seem to find my windows cd which is why I haven't already done it.
When I start up in safe mode with networking, I get the winlogon.exe error, although I do not get it when I'm just in regular safe mode.