I'm just bumping this thread as the problem still persists and if anything, seems to be getting worse!
The initial suggestion of installing the latest drivers for my Line 6 soundcard fixed this problem for about a week but then it returned.
Just a quick recap on the actual problem, whenever I use my computer for an extended period of time on an audio-heavy program such as a game, after an hour or so, the audio stops working and any program (be it the game or anything else on the computer) that uses audio will also stop working. This somewhat cripples my PC and the only way to resolve the issue is to restart the computer (which essentially restarts the Windows Audio Service).
Anyway, I have discovered I am not alone with this problem and there are quite a few people with the same issue but there seems to be no one piece of software and/or driver that can be identified as causing a conflict. The problem seems to happen on lots of people's computers regardless of system specs. In fact I have posted on two separate threads on the Microsoft Answers site where others have the same issue: Sound Suddenly Cuts Out After Gaming - Microsoft Answers
and Audio stops working but works after a reboot - Microsoft Answers
That second link has 6 pages full of people complaining about the same problem (admittedly the thread is a little clogged up by people posting DX Diag reports). The main annoyance with this audio problem is that it seems to be completely random and difficult to reproduce on purpose (for example if the problem only occurs when using a certain program then you could just disable that program to see if it stops).
Sometimes the audio can stop even when I'm not gaming and haven't really done anything on the PC apart from turned it on and left it on the desktop for half an hour. It's getting to the point now though where it is really affecting my ability to play a game. I use Steam and have a lot of games on there and have recently started playing Skyrim, but now whenever I play the game the audio will stop working after a while (sometimes it will be fine for a few hours, other times it can happen rather quickly). Because of this constant interruption and being forced to restart the computer, gaming is completely spoiled and I can't make any real progress in games.
I don't think the problem is anything to do with my soundcard's drivers (I have the latest version and constantly check for new one's) and I have other sound codecs etc from the K-Lite codec pack. The only other sound devices listed with my default playback device (the Line 6 soundcard) are 16 instances of SndTAudio which is something that my Soundtaxi audio conversion program uses. Could this be causing the problem? I don't know why it's listed 16 times but I have used it before with no real problems and I can't find any reference to it causing a problem on Google.
This is driving me mad and I'm really hoping to avoid formating my hard drive and installing a fresh copy of Windows due to the sheer amount of stuff I have on my PC and the length of time this will take, plus there's no guarantee that this will fix the problem as it may occur again once I get everything re-installed.
Does someone out there have any idea what I can do to sort this out? I'm sorry for the long post but I'm trying to give as much detail as possible in the hope that someone can help.
Thanks for any replies.