Randomly lose all audio

Hi,

The past month my laptop developed a very strange problem that has me baffled. Randomly I lose all audio and to restore it I either have to restart the windows audio service or restart the system.

It happens randomly but once it happens the first time it keeps happening again and again, if that makes sense. So my guess is something is triggering the problem. What happens is that the audio device becomes unresponsive in the sense that it is being used by another application (or so it says).

Common scenarios:

* I am watching a video and then I switch to another video -> no sound
* I am in a skype call, the audio of the call is fine but everything else -> no sound

When this happens trying to play the test tone in the audio devices results in, the device is being used by another process (or something along these lines)

Things already tried (or things that might be important to note):

*Reinstalled audio drivers
*Unchecked option to give exclusive access to applications in the sound device
*Removed a number of recent windows updates
*Happens with both the integrated sound card and an external dac (Nuforce uDac-2), so it's not device specific
*Checked the system for errors with chkdsk, no problems found

Any ideas?