It looks like Windows 7 can set different sound volumes for different apps. I think Vista did it too but I neved had issues with it.
Now in 7 I have a problem: I load TeamSpeak and then I enter Left 4 Dead. As soon as we start a match, 7 decides that TeamSpeak volume is too high and it reduces it to around 20% (all appz are around 80%) so I can barely hear my teammates. I alt-tab out of the game and manually raise it to 80%, so I can play and talk normally.
But when we finish one level, surprise, at the start of the next level Windows 7 lowers volume of TeamSpeak again, so alt-tab again and raise volume.
Can this "feature" be disabled?