Most problems I have had with steam/source engine games.
Have been solved with a local file check or by deleting the .blob files in the steam root directory and restarting it.
This seems like a local files check.
Just open up the steam library and right click tf2
choose properties
then go to the local tab
and click 'verify integrity of game cache...'
See how that comes back
Also it never hurts to just restart steam, it could just be something wierd in the steam cloud. If it hangs trying to sync when you close it, that is likely the case. Steam cloud problems can affect game settings because of the way steam stores them now.