i'm using a pc with radeon hd4870. its connected to my main monitor via dvi and to a sony s360 receiver via hdmi (5.1 home theater system) which is connected to my tv(my secondary monitor). when i want sound out of the speakers i have to turn on both the receiver AND the tv. i used to be able to play sound out of the speakers without turning on the tv, but i dont know what had changed. can anyone help me out please? thanks!