Microsoft is offering updates designed to resolve issues preventing users from upgrading Windows 7 with the addition of Service Pack 1 (SP1).
"When you try to install Windows 7 Service Pack 1 (SP1) or Windows Server 2008 R2 Service Pack 1 (SP1) on a computer that has more than 10 language packs installed, the computer stops responding at a black screen. Additionally, you receive an "0xC0000009A" error message," stated Microsoft in KB2534366.
"This issue occurs because the number of open registry key handles for subkeys that have the same name is limited to 65,535 in the registry. Each language pack that is installed on the computer increases the number of open registry key handles."
You must install this fix in order to to resolve this issue before you install Windows 7 SP1 or Windows Server 2008 R2 SP1.
In another issue releated to the installation of SP1 for Windows 7 and Windows Server 2008 R2, the desktop can freeze or restart to a black screen of death, with "0xc0000034" error message being logged. The company in KB article KB2533552 notes that this only happens after SP1 is deployed, although it's also necessary for users to:
Install some other updates before you restart the computer to complete the installation process. Or, the service pack is installed at the same time as other updates by using Windows Server Update Services (WSUS).
Microsoft has identified the source of the problem and is now providing an update to resolve the bug:
This issue occurs because Windows tries to perform operations in the Primitive Operation Queue (POQ) two times during the service pack installation process. The second attempt to perform these operations fails (because the operations have already been performed). Therefore, Windows generates a "0xc0000034" error.
The update to fix this issue is available from Microsoft Update website.