Does the PC get shutdown properly, or does it just get powered off with the ignition?
If it just gets powered down, Windows may not save your settings. In this case, do a proper shutdown and that should solve it.
Also, do you have real player installed? I've had this cause problems on tons of PC's. If you do, open real player and do two things: 1) Disable smart center all together. 2) Before closing real player turn the volume up in RP all the way.
Otherwise I'm out of suggestions right now...