I'm having a similar problem. Same TV, also on Time Warner, but with the slightly different 8240HDC DVR/set-top box. Output from the box to the TV is through HDMI-1. 50% of the time, I power on the TV and DVR and I get audio and video. The other 50%, I get audio only. I've tried different HDMI inputs and cables, and it's not those. And my DVR audio output is also set to HDMI. I'm now using the composite inputs on the TV, and that works fine but with some degradation in signal quality. I called LG tech support and was told, "yeah, we've seen that before. The only solution is to set your DVR to output at 720p resolution." That's a stupid solution, and it doesn't work, anyway.
I'd guess this is a firmware glitch on the TV. The TV is "hunting" for a signal from the HDMI cable and apparently can always "grab" the video but sometimes misses the sync with the audio. Desperate for a solution here.
Puzzling issue with my new 55LW5600 TV connected via HDMI cable to a Time Warner Explorer 8300HDC DVR.
On power up, the TV has no audio from the DVR on HDMI1. Audio OK from my LG BluRay (Connected to HDMI2) Picture is crystal clear with no glitches on both inputs.
If I select HDMI2 (BluRay), allow it to connect, THEN switch to HDMI1 (DVR), I get audio from the DVR.
I have tried different HDMI cables, and have swapped outputs between the BluRay and the DVR. I have also verified the DVR is set to HDMI audio.
Anyone else have this issue?