Hi, this has happened 2-3 times before, i have a vizio tv with an onkyo receiver utilizing hdmi on windows media center windows 7. I accidently hit something on my windows media center remote and lost sound. I tried to restore windows from a previous date, no mutes are on. Its so frustrating. I have done the right click on the speaker icon but still nothing, it happened in the middle of the program. can anyone help? one last thing, i updated the ceton drivers and i had sound - the next morning it was gone