WindowsUpdate_00000643" "WindowsUpdate_dt000

Hi BrunoZschauer,

1)       How long have you been facing this issue?

2)       Which Windows Updates are you attempting to install? Please provide the Knowledge Base (KB) number

Method 1:  You may follow the steps mentioned in the article below

You receive error code 0x80070643 or error code 0x643 when you use the Windows Update or Microsoft Update Web sites to install updates

http://support.microsoft.com/kb/958052

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base
How to back up and restore the registry in Windows

Method 2: If a Windows Resource Protection (WRP) file is missing or is corrupted, Windows may not behave as expected. Run System File Checker (SFC) scan to fix any corrupt system files. To do this, follow the steps mentioned in the link below:

How to use the System File Checker tool to troubleshoot missing or corrupted system files on Windows Vista or on Windows 7

http://support.microsoft.com/kb/929833