Bell says move it
I called Bell again and the peson i got this time suggested i move my pvr to the other room upstairs and connect it to another satellite line. Just in case there's something with the switch or other issue with the normal location.
So far it hasn't rebooted again (~8hours).
We'll see. If I don'e notice it rebooting by tomorrow, I'll probably move it downstairs again tomorrow afternoon (game 2 playoffs to watch on the big screen).
If it does come back I will try pointing a fan at it.
[I'm going to keep trying a few things as my pvr is out of warranty - bought it Dec2008]