Shutting Down Windows 7 Started Taking 20-30 Seconds

My PC started taking ~30 seconds to shut down recently. This never happened before. I must add that it doesn't always happen. If I restart / shut down soon after turning the computer, it shuts down in under 5 seconds. But if I use it for several hours then it takes half a minute or so.I can't think of many things I changed, but I remember installing a number of Windows updates and also new Catalyst 12.10 video card drivers.Things I've tried: Checked the "ClearPageFileAtShutdown" setting, it's 0. Tried this tutorial and used the 2 second thing, no change. Enabled verbose startup, shutdown, logon, and logoff status Messages. This was pretty useless as when shutting down it cycles through "Stopping services" and other stuff faster than I can read, but then gets stuck on the "Shutting down" part, not very informative There doesn't seem to be any hung apps because I get no prompt to end task (I got that a few times before, and it seems to happen way before it goes into the "Shutting down" message).