You might also want to take a look here to troubleshoot the problem. Please read the comments on both links in their entirety if you want to try and troubleshoot the problem using a “clean boot”

Reliability history reports Windows is not being shut down properly.

Make sure you expand the replys and go to the “clean boot” link (2nd link on this post)


http://answers.microsoft.com/en-us/windows/forum/windows_7-performance/reliability-history-reports-windows-is-not-being/890189c1-3120-45b8-9af4-561dfeeedc7d

To help troubleshoot error messages and other issues, you can start Windows Vista or Windows 7 by using a minimal set of drivers and startup programs. This kind of startup is known as a "clean boot." [b]A clean boot helps eliminate software conflicts[/b]. This article describes how to troubleshoot problems in Windows Vista or in Windows 7 by performing a clean boot. This article also describes how to start the Windows Installer service and how to reset the computer so that it starts as usual.

Note When you perform a clean boot, you may temporarily lose some functionality. When you start the computer as usual, the functionality returns. However, you may receive the original error message, or you may experience the original behavior.


http://support.microsoft.com/kb/929135