You have failed to advise what operating system including SP level of the
computer this problem is occurring on.
Perhaps try resetting Windows Update and see if that fixes the problem
How do I reset the Windows Update settings?
http://support.microsoft.com/kb/971058
if not, please post to Windows Update forum and don't forget to advise what
OS you're using etc.
http://social.answers.microsoft.com/Forums/en-US/categories