I have this problem with playing back animations in blender. I use linux, with KDE3 as my windowmanager.
Whenever I press “play” nothing happens. I suspect the window hides behind the blender main window, since I always have to retrieve a rendered stillframe with alt-tab. When I do not use KDE3 it all works fine, but not starting a windowmanager is not really practical.
I had a similar issue with Redhat 7.3 and 8.0. In the end, I ignored it and played rendered movies outside blender in xine. I know it’s a bad solution, but it’s the only one I can give. Mac rendering/playback in a window doesn’t work at all. AFAIK the only platform where this works well is Win32.
I didn’t have this problem in KDE2, so maybe I should start complaining to the KDE developers. Maybe I’ll drop a note here if I have a solution, except if nobody cares .