Troubleshoot Windows Update, Microsoft Update, and Windows Server Update Services
When you use Windows Update, Microsoft Update, or Windows Server Update Services (WSUS) to install updates, you may experience one or more of the following issues:
You are offered an update for a product, but the update is not downloaded or installed on your computer.
You are repeatedly offered an update, even if you have already installed this update multiple times.
A particular update failed to install.
KB906602 discusses how to troubleshoot these issues.