I just mentioned the cable, as I took a heavy duty cable that had seemed to work fine on my system to my mother's last year to hook up her new HDTV. It worked fine for a while, but then she kept losing the signal. I changed the cable and it's worked fine since then. Not sure if the cable went...
Cables can go bad, especially if they're moved and connected/reconnected often. I'd try a new high-speed cable.
Since this is Canada, I don't know if there are issues with the digital copyright management stuff? I had to set my new 4K blu-ray player a certain way to get it to work with my TV...