Ever since Steam updated a little while back I've been having a lot of trouble with the overlay. Simply put it just doesn't boot up half the time I start a game. This can only be fixed by restarting steam. According to the Steam forums I'm far from the only person with this problem but no one has any idea how to fix it.
Is anyone else having issues? One possibly cause mentioned was that closing tabs in firefox or running firefox in general might cause problems.