I think that Windows might be disabling my sound device during gaming because it thinks it is idle. I don't know if this is the exact reason but after much testing have come to this conclusion.
Anyway, the problem is that while playing some games (for example Borderlands, Civ 5) the sound will be fine but after a while playing the sound will cut off completely. It seems to occur when I am playing a game for more than an hour although I can't be very specific. If I exit the game and try to play an MP3 etc in WMP then the program just behaves like it's trying to do something in the background and won't actually play the file. There are no system sounds or any other sound at all.
This doesn't happen in all games, for example, when I play Audiosurf then the sound plays as normal no matter how long I play. This is why I think it may be a Windows issue thinking my sound card is idle and then turning it off because when I play Audiosurf, the game plays my MP3 files and so presumably Windows knows my sound card is in use but when I play any other game that just uses the game's own sound files/effects, then Windows isn't recognising this and after a certain period of time is then disabling my sound card.
Does anyone know of a solution for this or has come across something similar? I have an external sound card that is connected via USB (Line 6 Toneport UX2). Let me know if you require any more system specs, oh I'm using Win 7 HP 64bit btw.
Please can someone help me with this as it's driving me mad and when gaming online and chatting to my friend through Skype, the sound will suddenly just go off. While he can still hear me talking into the mic, I can't hear him or the game's sounds/music and he has to resort to typing me messages in-game.
Sorry for the long post but I wanted to try and describe the problem in as much detail as possible. Thanks for any help.