http://www.microsoft.com/windows2000/techinfo/administration/security/msgina.asp
Recovering from a GINA-related System Failure
Recovery is possible without reinstalling the system. This requires having a boot disk, or equivalent workaround, that will boot the system without using a normal hard disk boot.
To recover from this situation:
1. Boot the auxiliary system—potentially by using a boot disk.
2. Go to the System32 folder where the new, failed GINA DLL is located.
3. Move the failed GINA to a different folder.
4. Copy the original MSGINA DLL in the System32 folder and rename it with the name of the failed GINA.
5. Restart the computer and the original MSGINA DLL will load under the new name. At this point fixes can be made in the modified GINA.
