there are MANY reasons for the sound loop crash in source games and they can be different for everybody. i decided to mess with sound settings in vista, i unchecked all the boxeds under "Exclusive Mode." went from INSTANT crash in TF2 to playing for over 1 hour. i confirmed by reversing this and again INSANT crash when entering server. AA and AF causes crash also in my case, so these are also turned off. HDR also off/none.
