Hi
Thank you for Contacting Microsoft Community
Windows update installation basically happens while system goes for shutdown
Could you please update what has been set for windows automatic update.Change the setting to ""Download the update but let me choose when to install""in by going to control panel windows update and click change setting
chances are it is something (3rd party) that you installed that is causing it.
If you re-install but add the same programs back it will return.
You might want to re-install and then re-install one thing at a time until the problem start again, that way you will know what is causing it.
Try this Also
Step 1: Disconnect all the external devices (printers, scanner, USB (universal serial bus) drives, etc...) Except mouse and the keyboard and then boot up.
If this corrects the issue then add the devices back one at a time until you discover the piece of hardware causing the issue. Then get any updated drivers\software for the device.
Step 2: Put the computer in clean boot to figure out the problem causing program
Follow Step 1 in the link below,
How to troubleshoot a problem by performing a clean boot in Windows Vista or in Windows 7
http://support.microsoft.com/kb/929135
If everything works fine after a clean boot, you can infer that some third party services are causing the problem.