Unfortunately, I don't see the same thing.
We disable the screensaver if:
* We're in fullscreen Display View OR
* The display is detached and in fullscreen OR
* The UI mode has been changed in the last one minute
I can't see why Playing Now in Theater View, while stopped, would do anything special.
Have done some more testing.. even just having "Cover Art" at the bottom of the playing now screen does the same thing... screen saver is on and as soon as playback stops screen saver turns off and then never comes on again.
Not sure what else I can tell you, happens on three different PCs, all running XP SP3.
I start playback from Theater View by drilling down to the album tracks and then select Play All on the first (or any ) track.
Playing now screen is then displayed and after 5 minutes screen saver starts. At end of last track playback stops and so does the screen saver.
Start playback again and then screen saver with come on again.
Richard