I'm using an Ubuntu 12.04 LTS. Since, I discovered that there are other desktops on Ubuntu, rather than Unity, I installed Gnome 3.4.
But it freezes time by time, when I run many applications or little. Sometimes I can enter into no GUI with Ctrl+Alt+F1 and to restart my GDM, sometimes not, but my music is still playing in background, so I think kernel is not blocked, it's a GPU problem or maybe another. Please give me some advice or maybe you know what the problem is and the solution.