I've had a S3 since they came out, now equipped with a TA.
Tonight, out of the blue, while watching a recording, it blackscreened. No video output, no lights on the front panel, no ethernet lights on the back.
I power-cycled it; the fan is running but nothing seems to be happening after 20 minutes.
Possibly coincidentally, when it blackscreened I noticed the TA indicator light was blinking. It reset after a power-cycle of the TA.
Our other TiVo, a HD model, seems to be OK.