hi, here's my problem: the rear channels used to work but just lately it won't. and the only thing i have done between the time they were working until now is: 1) i've reinstalled WindowsXP (using the same WHQL .632 driver before this happened), and 2) upgraded my video drivers to WHQL detonator 40.72. i know this must have nothing to do with the video drivers but really that's all i have done before this happened! i've double-checked the volumes, used different headphones, have not installed anything 'cept the drivers (it's a fresh install of xp). could this be a sudden hardware problem? any suggestions?