Why am I receiving "Error C000009A" after installing Windows 7 Service Pack 1 (SP1)?
“After installing Windows 7 Service Pack 1 (SP1), you might receive the following error message on a blue screen:
"Error C000009A applying update operation {###} of {###} (\Registry...)"
To resolve this issue, restore your computer to a point in time before you installed Windows 7 SP1, uninstall any unused language packs, and then reinstall SP1. To restore your computer to a previous point in time, you'll need to use the System Recovery Options menu.”
Read more about error C000009A and how to resolve the error
rob