Done cold reboots, but did not check signal strength. But I did break down and called Videtron, which is sending a technician on Tuesday. They noticed that something has changed with my SA8300HD since July 26th (No longer returning info or something?), which is probably when the problem began.
Another cold reboot last night helped improved the image/audio a lot on the problems channels, but I can still see/hear a slight corruption which makes me suspect it may be a problem with my SA8300HD unit.
BTW, if I buy a new SA8300HD unit, will I loose all the shows recorded on my external eSATA drive? i.e., are they encrypted for this exact SA8300HD unit?