If you press resume play when program is playing lockup
If you use exit key to back out while playing a program and press "resume" to enter full screen again the circle will keep showing waiting and nothing happens (you get stuck). If you click play, the video is restarted from the beginning.
I know if you click on the video window in "Recorded TV HD screen" it ill resume full screen. Maybe the play and resume button should be remapped during play back to show the episode full screen?
When you click the "play" button from WMC recorded TV while the same video is playing, the video goes full screen.