Do I have a hardware or software/firmware problem with my Panasonic TU-CT20 DTV converter, or do I have a reception problem? Symptoms are: If subtitles are switched on, after some hours (4 commonly) they start to slow down and eventually freeze altogether. If nothing further is done, then a few hours later (3 commonly) the picture itself freezes. The sound performs normally at all times. The only way to unfreeze the set - no controls are by then effective - is to interupt the DC power to the unit. No pixelation is seen on the picture at any time. And the 'signal quality' on 'setup' is fine - all green. In all other respects, if I don't use the subtitles, the unit performs correctly. After discussing the problem with the Panasonic factory helpline, I've just exchanged the unit: the same symptoms are apparent. Can anybody throw any light on this?