Try using autoruns (to see what is automatically started) in the dave profile. Also plain task manager might help to see what's wrong in your profile when shutting down: launch it, order the processes by user and, after closing all applications (those you're usually launching) and before shutting down your computer, check the processes launched by your account in task manager. Try killing one (from the most suspicious) and the launch the shutdown. If the shutdown is fast then you get the culprit, if not reboot and do the same thing with another process. As a side note, what antivirus do you use as i've seen this behavior with some antivirus (like MacAffee and its "scan floppy before shutdown" option that will hang forever searching for a floppy disk on recent computer).