Not an expert either. Did the problem appear suddenly? Did you make any changes recently - hardware, drivers? Do you have SP1 installed, it contains a shutdown patch (seperately available
here ), but that's probably not the problem.
Guess you'll have to do a step by step search for the culprit. First close all programs manually, including those in the systray, before shutdown. Then I'd try to change drivers (one by one). Some more links on the topic:
click and
click
Perhaps someone else has more ideas what to look for and will jump in.