Logitech Z-550 - Rear right speaker pops loudly, kills sound

I've got a set of 5.1 Logitech Z-550 speakers. What happens is the back right speaker in my setup will suddenly, without any warning, start popping loudly when I have sound going. First it'll pop once, then there's a short delay. Next the popping gets louder and more frequent, and eventually, the speaker will pop about 20 times rapidly before all the speakers go dead and the sound stops completely.

The control pod stays on, but there's no sound. Turning off everything from the subwoofer, waiting a little, and turning the sub and the control pod back on will temporarily fix the problem.

This first happened a few months ago, and I kept the sub off for about two weeks before deciding to turn it on again. The speakers all worked and the problem went away until now. Now I can't keep the speakers on for a minute before the back right speaker pops and forces the sound off.

Does anyone know what it could be? I've isolated it to that speaker, and I've rechecked all of the wires multiple times. I believe I have the latest drivers but I feel that this is likely a hardware problem, I just don't know what it could be.

New: Ok, something interesting I've noted. If I have headphones on, the audio will stop, but without the popping. Could this mean it's not an issue with the speaker, and possibly with the sound card or driver?

I really appreciate any help.