If you switch some times between tv guide and full screen tv (which is quite usual) - it takes several times to go back to the menu using the back button because it toggles for some time between tv guide and tv fullscreen according to the windows history.
That is quite annoying.
TV Guide should only appear once.
We should generally prevent storing same sequences of windows in the history.
Assume the following history:
1) tv fullscreen
2) tv guide
3) tv fullscreen

if one hits the tv guide button it shouldn't be added to the history.
Any other window would be ok though