Updates not Installed on Shut-down
Although the auto-update seems to run fine and download all that’s needed, sometimes it fails to install during the shutdown process; it seems as if everything is fine but on restarting the process repeats, asking to shutdown again and install the same updates.
You can empty the temp folder used by Windows update and retry to install on restart. In order to do this follow these steps:
Go to Start, then All Programs -----> Accessories -----> Command Prompt -----> and finally click Run as administrator. Continue if you receive a notification (User Account Control notifications can be disabled).
Type or paste the following command at the prompt:
net stop wuauserv
ren %systemroot%\SoftwareDistribution SoftwareDistributionold
net start wuauserv
You can also check if the updates were actually installed and you don’t need to run it again. Do this by accessing the Control Panel and looking in ‘Windows Updates’ to see if anything was installed successfully.
You can also try a more thorough clean-up described below.
You can read the following Microsoft Knowledge Base article for more specific information; note that the article applies to versions of Vista, XP and previous but since the update routine is similar it usually works for Windows 7.