My ps3 mic broke, I think the problem was the charging dock connected to the usb. If you turn your system on and off alot during the day even after the mic is fully charged once you turn it on it still flashes and charges it for 5-10 minutes, do that enough and you will fry a battery. My advise is once fully charged , don't charge it again until its almost dead or just don't push it into the charging cradle all the way, this go's for almost anything with a battery, charging it when not almost fully drained will eventually make the battery life super short and or kill the battery. I'm using the plantronics discovery 925 now.
I'll go ahead and assume you're right and say that's exactly what happened to mine. Sounds very similar.
