I have an unmodified HDVR2. It's seemed a little flaky over the last year or so, but nothing major. I moved two weeks ago and it's been in a downward spiral ever since. Initially I thought the reboots were because it was unhappy about not having the satellite connected (I just got DTV at the new house today) but they became more and more frequent of the course of the two weeks.
Initially it would just reboot. Then it would reboot, but stick on the "Powering Up" screen. After a hard reset it would come around. Then it would take a couple of hard resets to come around. Now it just won't. I tried initiating a self-repair (hit pause during boot, type 57, got the green repair screen) but it's still just as busted.
I'd already been planning on upgrading the hard drive so I'm ordering a new one now, but I'm wondering what the odds are that this is the power supply, instead? My reading here leads me to believe it's one of the two.
ETA: I've opened it up and checked the cable connections, they're all secure. Bummer, since I was sure it had to be something dislodged in the move.