More HD woes

I'm not sure now if its the TV or my cablebox that is causing all these problems. This weekend i'm going to borrow my dad's ps3 and watch a blueray movie like spiderman or something and see how it looks. ...because last night I was watching all night on it and had no real eye strain. I was watching a Terminator 3 which clearly has a lot of action sequences and didn't have any of the stuttering I thought I saw on Monday, though it was a low def signal. Also on the hi-def side I didn't see any real problems watching mythbusters, other then that it seems that after a while watching a saved show on my DVR the video will freeze up but the audio will continue. Also sometimes when i'm in guide view, the preview window in the top right doesn't expand to full screen when I leave the guide (that definitely sounds like a bad box to me). Could these problems be a sub par HDMI cable? Hmm I dunno. Hopefully some of these questions get answered this weekend?