Your best option may be to take advantage of Microsoft's policy of free support for issues that invove Windows (or any other MS product) Updates.
There are several reasons why updates may not install from a corrupted update engine (addressed in previous updates) to services that are set "off" in your registry to problems with Internet Explorer.
The folks at MS will walk you through the repair process.
Microsoft Security Product Support Policy
Technical support is available from Microsoft Product Support
Services at 1-866-PC SAFETY (1-866-727-2338). There is no charge for support calls associated with security updates.
International customers can get support from their local Microsoft
subsidiaries. Phone numbers for international support can be found
In addition to the phone number you can access support by going to the Windows Update site and clicking "Get Help and Support" on the left side of the page.