My symptoms don't *seem* to match anything previously posted.
* Pre-recorded shows which used to be fine will stutter and freeze.
* If I reboot, said shows will work okay... but then fail again later.
* Live TV is affected (goes gray, fixed only by channel changing) when a pre-recorded show causes a freeze.
I ran a kickstart 54 and got an error code, but I've heard that SMART can give false-positives, and the disk is only 3 months old, so I'm loathe to just replace the disk. I managed to reinstall the OS with kickstart, thinking the drive upgrade (copied from a known-failing previous one) may have corrupted things. (And kickstart 57 didn't seem to do much.)
And the unit's temperature is fine (41C) --> I've seen and fixed that problem before.
I will be opening it to check for blown resistors, if any are puffy, then I guess it's time to shop for a new power supply. I can't find anything out there cheaper than $99... ouch.
If anyone has additional clues, I'd appreciate hearing about them.