First try this Microsoft Fix-It:
- Right click on the task bar and go to Task Manager. (Alternatively press Ctrl+Alt+Del and select Task Manager.)
- Click on More Details at the bottom left and then click on the Services tab on the right.
- Scroll down to wuauserv or Windows Update.
- Right-click and go to Stop.
- Now open up Computer by clicking Start and Computer.
- Navigate to C:\Windows by double clicking on Local Disc C:\ and then Windows.
- Scroll down until you see the folder SoftwareDistribution.
- Rename the folder to something else: IE: SoftwareDistribution-OLD.
- Now restart your computer and try Windows Update again.