Some applications have the audio cut off when the window isn't active. For example, games. If I run a game in a window and (without minimizing, leaving it open) if I activate another window the audio to the game cuts off. I have to activate the game window before I can hear the audio again. Even though I can see the game and all the 3D is being rendered, I hear nothing when I activate another window.
The same game, however, would still play audio even if I activated another window in Windows XP.
I also noticed that under Windows 7 when I right-click the audio tray icon I can select "audio mixers" and see all the applications that use audio. Can like dissable this, and just have all of the applications send their audio to one channel? That might fix my problem.