All Sound Stops When I Leave Champion Select?

This includes vent and regular music. It start happening a while back and does not happen everytime. Any guesses? Has someone else posted this problem?

I'm still having trouble with this, any help from the community would much be appreciated!

Here are more specifics:
1) When the game moves from the PVP Client into the load screen the problem occurs.
2) Either everything works, I lose all sound, or get an annoying and loud buzzing sound.
3) The above problem is more likely to occur if I have vent open or other programs--especially itunes.
4) Once the problem occurs in game, there is no way to remove it from the game (even if I reset the computer) and it is likely that all subsequent games will have the same problem until I reset the computer.
5) This has only ever happened with LOL

Besides updating my drivers and turning on and off all the options, I don't know what else to try! Not being able to talk to friends on vent while playing means either that I need to get another computer (that could run vent) or that I might stop playing LOL. Please help me! Any new ideas?