Ubuntu 12.04, ThinkPad Edge 15

I've been having this issue for a while now, but it only happens occasionally and at seemingly random times. My computer will mute/unmute itself repeatedly over the course of 5-10 seconds, even if I don't touch it. When this happens, any keypresses or mouse clicks are either extremely delayed or completely ignored. Sometimes clicks will be triggered, and other times it will act as if the ALT key is being held down (for example, scrolling in a window will change the opacity, which is something I have set in Compiz for ALT + scroll).

I have no idea what causes it to happen, nor can I find any relevant logs. Usually I end up restarting my computer out of frustration, but sometimes that doesn't even fix it and the behavoir will persist for a little while after logging in. I've tried Googling for things like "ubuntu random keypress" and "ubuntu spontaneous mute unmute" with no luck.

This does not happen in Windows.