I have a Motorola HD PVR (model DCX3510-M) that I received from Shaw in 2013. About one week ago it began rebooting multiple times a day. On a few occasions it has displayed the message "Rebooting STB. Please wait..." but in most instances it will simply become unresponsive and reboot without warning. The problem seems worse if I press the "Live" button on my remote to scroll through my list of recorded programs or try to play back a recorded program, but if I'm watching live TV the video will sometimes become choppy and out of sync with the audio and then freeze, and I know another reboot is about to happen.
Rebooting by the normal method (i.e., unplugging the DVR, waiting a few minutes, and plugging back into power) will solve the problem temporarily but only for a few hours.