Vista won't go to sleep when idle

I'm using a custom power profile (though this issue occurs regardless of
what power plan I have selected), I have my notebook set to sleep after
10 minutes when on battery and 30 minutes when plugged in. It never
goes to sleep when idling any more.
I know about the media sharing issue and I've changed both of those
settings to allow sleep when sharing media.
This issue does seem to coincide with when I hooked up a media extender
(XBox 360) to my home network. I don't know if they're causally
related. Hooking that up created an "away mode" that I'm not using either.
Yesterday when I was running on batteries, I forgot about the computer
and it just kept running until the batteries died.
The computer has no problem sleeping when I tell it to do so or when I
close the lid. The issue above is what concerns me. I don't want it to
just run down.

Background apps include Creative Sync Manager, AVG Free Edition (Virus
Scan), ATI display manager, Windows Sidebar
All of the services running seem relatively normal and there don't
appear to be any event viewer logs reporting a failed sleep attempt.

--
"Out here on the perimeter there are no stars"

Steve --Inglo--