The first sign of a bad cable box (or bad cable signal) is often in how it responds to IR. Think of a computer that's really "busy" or "bogged down" while you are trying to type a document or move the mouse...it reacts sluggishly. I have never had an HD8300 that I couldn't get working flawlessly (and i don't usually have to try to hard or move the emitters or anything) so I'd start with the cable signal, then the box.