you need to stop and restart the windows update service....
type " net stop wuauserv " (without quotes)
wait a couple of minutes
type " net start wuauserv " (without quotes)
If it does not work the 1st time just repeat it 2-3 times
that should give it the boink it needs to get going and do it
be sure to shut off your antivirus just in case it is hindering the process also....