QUOTE(Vash3k @ Apr 19 2009, 10:53 PM)

It is your TV. Mine does it too. I'm using a Toshiba 42" and this problem constantly pisses me off. It has to do with the fact that sometimes, when software is switching modes, it halts the video signal to the tv (that moment where the screen is black) and the tv resets its mode when it detects a new signal.
So are you saying Toshiba TVs wont display games in widescreen? I just got a Toshiba hl167 and setup my Xbox . Ive had trouble with games not displaying full screen and I came across this thread when looking for possible fixes.
In any event if that is not the problem, Im using the Ndure Softmod Through Xboxhdm and using NDure 3.1 I have changed the settings in the MS dash to allow 720p and 1080i. When I boot up the Xbox the main Xbox screen is still 4:3 but when it goes to XBMC it displays as 16:9. When I go to start up a game like Halo 2 or any other widescreen game it reverts back to 4:3. If I go back and check the settings on the MS Dash they are still showing 720P and 1080I as being enabled. Im at a little loss on whats going on here.