Hi glovebox,
My first thought is maybe hard drive? It could be a corrupted buffer on the partition that provides the continuous 2 hour pause/rewind. When did you last reformat the hard drive? If it was a long time back, then maybe reformating drive will solve problem.
One test you could try is unattach the hard drive & see how the pvr works without hard drive connected and doesn’t show the screen problem. The only other options are disk cleanup, via settings menu. Not totally sure if this will do anything, but worth a try. The other options are factory reset, but if this fails, then pvr needs a repair. Also check HDMI cable & if you have a spare one, maybe try this. Hope I have been able to give you some help. Please let forum know how you get on/if you need more help. John L