I've setup TV out as best I can, and I still have this problem:

While watching live TV, I hear the sound, and I can change channels. But 95% of the screen is a black rectangle. The only part that shows the TV is a thin streak around the edges of the TV area. It changes rapidly with the sound, so I know it is the TV that is showing. Most of the middle of the screen is this fixed black rectangle.

The frontend displays fine on the TV. It is slightly smaller than the TV itself
because I fiddled with the GUI display size under "Utilities/Setup -> Setup -> Appearances". So the thin border area also shows while displaying the GUI. But
then the thin area is a fixed picture (the one where the penguin is watching the large screen TV).

The thin border doesn't bother me. The black rectangle is the problem: reading online it appears that this is because /dev/fb0 is overriding /dev/video16 or something like that. How can I correct that?

Solved: the solution is #5.4 on page

http://mysettopbox.tv/phpBB2/viewtopic.php?t=15195

and is also discussed in a post by cgremilin with the Title:

"Solution for a PVR-350 issue"

Basically it is to add:

options ivtv-fb osd_compat=1
to the file
/etc/mythtv/modules/ivtv

Thanks!