THe only time I have my HDTV (samsung) go to a blank screen and show 1080p logo is if my HDMI cable is loose or I forget to turn my receiver to the right video selection to get my HD DVR to output signal.
I wonder if you hook up your HDDVR with component method instead of HDMI if this would continue.
Try to see if your output (HDMI) is the problem first. If it drops the same way when hooked up through other options then you have a TV problem.
If it stays perfect then I think the HDDVR has a bad HDMI output.
Wish you luck.