I am having a similar issue. I have a Plantronics 777 Dolby Digital 5.1 headset that uses generic windows USB Audio for the SRS modular. THe other day I decided to download the MMO Runes of Magic to see if they had changed it since I last played and after the client patched it self...about 14 times and 4 hours later my USB audio suddenly started to go heywire. If I reboot its good...for about 5 minutes then goes from little scattered to just outright horrid. I have googled, reinstalled, uninstalled, etc etc and no avail. My question is could it had been the game client? Or just timing. Thing that sucks is I love these headphones/set but if I want the 5.1 to work I need to use the USB adapter.
so anyone know if its just windows being stupid or what.