Toshiba 32AV500U HDTV keeps losing channel 2.1

I'm trying to help out my elderly neighbors. Channel 2.1 (KCBS OTA - Los Angeles) keeps disappearing from the above TV. All other local channels have no problem. The only way to get it back again is to do a complete rescan, which then adds back in the multitude of Spanish and Asian channels which then need to be manually disabled. After the re-scan channel 2.1 has a strength of 97% and the picture looks great, but after a couple of hours the channel disappears again. It doesn't just get poor signal quality - it completely goes away, can't be manually tuned and once again it has to be completely rescanned. Rescanning and manually tuning out the unwanted channels is no easy task for an elderly couple and they usually end up calling me over to help. Their other two TV's have absolutely no problem with channel 2. They have a great antenna with pre-amp and proper cabling to all three TVs. I suspect a firmware issue because no other channels are having a problem and it is suspicious that only the first channel in the list is affected. Toshiba says there isn't a firmware update, however.

Has anybody else seen this issue or have a recommendation?

Elderly couples have had enough trouble with the HDTV transition, they usually can't (or don't want to) afford satellite or cable, and it's pretty aggravating they have to put up with issues like this!