Auto-muting problem

I'm dead tired and half delirious writing this, so I'm not sure how much sense I'll make, but I'd hoped I could find/get an answer here from -someone- finally about this bothersome issue.

I use windows 7 on my desktop pc, with a set of usb speakers, but they keep auto-muting me on everything I do for no readily apparent reason.

There's never been anything wrong with them since I've owned them.
This is the first time I've experienced a computer auto-muting without a cause.

It will randomly mute while I listen to music, it mutes at random intervals during movies/youtube/other online mediaplayers and it even randomly auto-mutes in the middle of games I play.

It also mutes the computer, completely randomly, when nothing is even going on it. As in, I turn of most of my programs before I go to bed so nothing is running and yet in the morning when I get up, it'd still muted itself overnight, while nothing was running. (Yes I leave my computers turned on for long periods of time, it's habit).

The issue started after I plugged in a new usb mouse.
Could my new mouse possibly be screwing something up somehow?

I'd just like some opinions out there on what you guys might think is going on, and if you can help then great, fantastic, I would love some advice.