If it starts to freeze regularly - and I mean multiple times a day - you're likely having an equipment failure. One of my HR20's started freezing up and couldn't go 15 minutes after a reboot w/o refreezing. Ultimately it just refused to reboot properly while I was troubleshooting and DirecTV replaced it.
If this doesn't repeat itself, I'd chalk it up to a random hiccup. If it repeats, then I'd dig further.
If this doesn't repeat itself, I'd chalk it up to a random hiccup. If it repeats, then I'd dig further.