JSI Tip 0907. STOP: c000021a due to System drive letter not assigned.

If you used Disk Administrator / Tools / Assign Drive Letter to remove the drive letter assignment from the system drive, you will likely experience:

STOP: c000021a {Fatal System Error}
The Session Manager Initialization system process terminated
unexpectedly with a status of 0xC000003a (0x00000000 0x00000000).
The system has shutdown.

To recover from your temporary insanity, you can NOT select Last Known Good.If you have a current ERD or repair folder, you can replace the System hive, either by running the repair process or using tip 505.If your repair information is not current, use Off-line Registry editing to load the original System Hive and select the Disk Key.In the right hand pane, select the Information, type REG_BINARY, value name and empy the value. Select your oldsystem key and unload the hive.

Shutdown and restart your original installation.