Okay here is a new bug I've seen twice now, and could be caused by several factors, haven't narrowed it down completely yet.
First off I've been running my game with AMD's Evolved Gaming App in the background "Raptr", which then fires up Steam.
Now if I start the game exit rather quickly, with-in 5 minutes everything seems to close fine.
If I play the game for 30+ minutes the game seems to close, however, when looking for what was draining my system I've found the game is still running in the background, doing what, who knows? Now this may be caused by Raptr or it may be a general issue with the game. I intend to do more testing tonight w/o running raptr to see if it still stays running in the background after exiting while playing for longer than 30 minutes.