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I will require some additional information to assist you better.
ØWhich is the update causing the issue?
In the mean time try the followuing troubleshooting steps.
Microsoft has released a new "Fix it" solution that should automatically solve your problems with Windows Update. Just click the link below and follow the instructions. How do I reset Windows Update components?
Perform System File Checker (SFC) scan which will help you in resolving the issue.
To determine whether the issue that you are experiencing is caused by one or more system files that are used by Windows Vista, run the System File Checker tool. The System File Checker tool scans system files and replaces incorrect versions of
the system files by using the correct versions.
Follow the instructions in the link below to run SFC scan.