Some months ago i read about a problem, similar to this. The answer for that problem was this: the overlay(?) mode can only be used at one monitor at a time. And only the the primary display can use it (where usually start menu is). I don't know why. For example: if you start an mpeg movie, with a program which displays picture over an overlay mode (like WinMediaPlayer), the picture will only show at the primary display. If you drop the player to the secondary display, it will show black screen, or in some case the picture will freeze. But the player will think that it plays correctly.
I don't know if this could connect somehow that problem to this, but i have an nvidia gef 8600gts and i cannot use avenue on all displays too, just at the primary.
But when i change settings, so the TV is the primary, the video is plays correctly at the 2nd display (TV - which actually is now the 1st) but there is no output at the pc's display. (which is now the 2nd display)
Hope i could help with this. Sorry for my English, i'm from Hungary.
