c000021a {Fatal System Error}, The initial session process or system process terminated unexpectedly.
Yesterday I had a case where a Windows 7 machine halted with
c000021a {Fatal System Error}, The initial session process or system process terminated unexpectedly.
0x00000000 (0xC0000001, 0x00010400)
This means that the login processes died for some reason. After trying last good configuration, repair mode etc. and nothing seemed to help, I started up with the Windows 7 BootCD and checked the registry by running regedit from the command prompt and loading the SYSTEM, SOFTWARE etc. hives from Windows\system32\config directory into regedit.
I noticed that the SOFTWARE hive was nearly empty except for some Microsoft keys.
Another blogger had exactly the same problem:
So I first tried to run Microsoft chkreg utility over a copy of the SOFTWARE hive, but it was unable to find corruption and fix it. An expanded chkreg.exe utility that can be used on the Windows command shell directly can be found here.
As this didn’t succeed, I tried to copy back the SOFTWARE file from Windows\system32\config\RegBack.
I wasn’t expecting it to work, as I thought that the Last known good configuration feature from the start menu would do the same, but it seems that this isn’t the case, so copying it back helped and the computer was ablt to boot up again.
Next step was to find out what has happened. I compared the broken and the good SOFTWARE file with each other and I noticed that they were nearly identical except for one page where its contents were empty in the broken registry file and were filled in the working backup file. I checked the Harddisks’ SMART values and found out that the HDD had 25 Reallocated Sectors. I suspect that there was a Relocation process going on on last shutdown that resulted in a blank sector to be written right in the middle of the Reigstry file which caused the corruption. Time to immediately change the HDD before it completely breaks down.
System programmer