I have an HTPC setup and use the coaxial output on my computer for 5.1 surround sound. Worked fine when using XP, but since the switch to 7 I haven't been able to get it to work. All my other sound is fine. I was thinking it might have something to do with AC3 because the icon for AC3 used to show in the task bar when watching movies back when it worked, and now it's going through DiviX for some reason. I have all the latest audio codec packs and use Media Player Classic for video playback. Thanks in advance for any help.