In tip 2596, the procedure to fix a changed boot/system drive letter requires that you be able to log on.
If you are constantly returned to the logon screen, use one of the following 3 procedures:
1. Implement tip 2615 and set allowallpaths = TRUE. Use the Recovery Console to create a Winnt\System32 folder on the drive that that you suspect has been assigned the original boot partition drive letter. Expand Userinit.ex_ from the CD-ROM to this fake \System32 sub-folder, as Userinit.exe. This should allow you to logon and use tip 2596.
NOTE: If the computer is networked, you can use one of the following. If the computer is NOT a domain member, you may need to map a drive to the 'broken' machine using net use \\remote_machine_name\IPC$ /user:administrator *.
2. Use Regedt32 on another computer to make the registry changes detailed in tip 2596.
3. Use Regedt32 on another computer to alter the Userinit value data at
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\Current Version\Winlogon
from C:\WINNT\system32\userinit.exe to userinit.exe. This should allow you to logon and use tip 2596.