I had this problem where Winlogon.exe would generate an error and
wouldn't boot.
I didn't find much usenet help, but was able to fix it with info from
this article:
http://support.microsoft.com/kb/156669
It indicates "It is very common for certain types of remote control
software to replace the default Windows GINA DLL (Msgina.dll)."
Boot to safe mode, and locate the following registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows
NT\CurrentVersion\Winlogon
· If the Gina DLL value is present and is anything other than
Msgina.dll, this probably means that a third-party product has changed
this value.
I had a value redirecting Gina to a third-party dll (laptop encryption
software was responsible for mine) which I deleted. I rebooted and
everything came up fine.
I hadn't seen this solution posted by anyone else when I was
researching the problem, so I thought I would post it.