Smplayer exits fullscreen

[drz4007]

Hello. After fresh install of 12.04 64bit, smplayer jumps out of fullscreen mode after playing for a while. Ii becomes "almost" fullscrenn, with the panels of the system at the top and bottom showing. I haven't made any changes to the preferences apart from selecting vdpau output driver. This behaviour didn't happen with my previous version, the 10.04 LTS. Does anybody have a clue? Thanx alot. (The same happens with totem but not with Gnome mplayer).