8300HD not talking to Sam LN-T4061 help!

I just bought a new Samsung LN-T4061F and also exchanged my old DVR for a high def DVR (SA 8300HD) (Cable service is through Time Warner). I hooked the cable box up to the tv via hdmi (Bought from monoprice.com) and tv source doesnt recognize cable box via hdmi. It recognizes the cable box when hooked up via composite video cables and s video. I hooked up my toshiba upconvert dvd player to the tv via hdmi with no problem. also swapped hdmi cables to ensure that wasnt the problem. Basically I narrowed it down to the cable box. called twc and they suggested unplugging everything then plugging in hdmi then plugging in cable box but that didnt work. today they said to bring in the box and they will test the hdmi port and if that doesnt cure the problem then they will give me an SA 8300HDC. Anyone run into this before or have a suggestion on what would be wrong? Oh yeah, I changed the resolution setting on the cable box while being hoked up via s-video. it was on 480i. I changed it to 720p and 1080i. It still didnt work. Thanks ahead of time for any suggestions.

Here is an update....turned in the 8300HD to TWC and received an 8300HDC. Plugged in HDMI, turned on box and it took forever to load and then there was a picture!!!!!!! Woohoo. Not so fast my friend....no audio. I found a thread on AVS about setting the audio to HDMI. So that is my next trick to get everything working. I did notice that when I switched from Standard to HD that the box switched resolution automatically. Almost there. I wish they would just give you this information at TWC.