Computer wont shut down

This may simply be a software issue. I would first try running msconfig and then disable all under startup and reboot the system. As a computer tech, I see this all the time. Windows is given a time slice to shut down all running programs before it can shut down and you may have a program or service that is not responding to this request.

All these items are normal items for things like your on-board sound, nero burning rom, plaxo (outlook or outlook express), MSN messenger, Norton AV and Office. The problem is knowing which is causing the issue (if any). I would disable all of them first and see if that helps. It may not even be any of these. It could be a driver for hardware that is causing the problem as well. If this doesen't help, look at your event viewer and see if you have errors in there.