hi i just bought a usb headset and when i plug it in it works fine but if i plug my g25 in all the sound goes and its not understandable and my microphone goes off

Your keyboard doesn't contain these two keys > ", ." ?

Did'nt you already make a thead like this?? It sounds like your overloading your USB docks, or maybe the G25 is robbing all the power and your PSU cant take it. Do you notice any performance issues when this is happening? Also, what USB version is yours, 2.0?