Fatal error (0000034) applying updates xxx of yyy 0xc0000034 _0000000000000000.cdf-ms

Ownoes, Shees,  f*ck..

I got this error on a Domain Controller,..
(ok, it’s a test environment, but i spent a lot of time testing in there 😉

http://support.microsoft.com/kb/975484

Perform the following actions in a system restore command prompt to fix:

Reg load HKLM\BaseSystem C:\Windows\System32\config\SYSTEM

Reg Delete “HKLM\BaseSystem\ControlSet001\Control\Session Manager” /v SetupExecute

Reg add “HKLM\BaseSystem\ControlSet001\Control\Session Manager” /v SetupExecute /t REG_MULTI_SZ

Reg unload HKLM\BaseSystem

Reboot,
OS Startup and system does update rollback
Reboot

(I also performed a

DISM /image:E:\ /cleanup-image /revertpendingactions

(/image:E:\ where E:\ is your root windows folder! do check. Win PE mounts drives in different order…)

from a system restore command prompt, but this step shouldn’t be necessary)

UPDATE:
Do not forget to try a install of 2008 R2 SP1 again !! The OS might say its SP1 but may have missed a few installs because of the error.