I sometimes have a similar problem. My 360 elite is completely stock. I have it hooked up to a SOYO brand plasma tv with an HDMI cable. However; sometimes during use, the sound will just cut out. I have to unplug the HDMI cable and plug it back in for sound to come back on. I have tried numerous different cables, but none seem to work. Also, it's rare that it happens, it doesn't happen everyday, maybe once or twice a month.