Seems to happen only when watching live TV. A box pops up on screen informing that the unit has been idle and wants to go to standby mode or I have the option to cancel this. I have checked for a recording in progress when this happens and there never has been one. I haven't put a clock to it but it seems to happen only once every few hours or so. I wouldn't consider watching live TV as idle but I guess the 3510 thinks it is.
I haven't attempted a power cycle yet. Have the Shaw techs seen this before? Do you think a power cycle will resolve the issue?