[powrcow]

I get that "channel loading" screen once the SDV adapter is up and working properly. It also dumps out any previous live buffers for some reason.

So it may be related to an SDV adapter (if you have one) or a cable card.

Edit: I'm on year 6 of my Premiere

 

[powrcow]

Is HDMI failure common on the Premiere?

The TiVo HD had more frequent HDMI failures. weaknees.com has a repair service set up to fix HDMI ports. You could probably contact them to see if they would repair it. But I would test different cables and TVs or monitors first.