problem playing mp4 files

[mahesh]

Hello,

I do not know if you have noticed that mp4 files cannot be played properly.

I tried using totem and the window opens momentarily and then it crushes, producing a bug which was filled using launchpad.
Using vlc, sound works ok, yet the screen is black. I installed also x264 package for vlc to no avail.
Ubuntu-restricted-extras package is installed in all these trials.
Installing mplayer it works only when invoked using terminal. The gui mplayer doesn't work.

Regards!