gnome 3 not work properly

when i updated my system(CLDG 11.12), it update the gnome2 to gnome3,
but when login in to the desktop, it gaven the warnning message like this:

*GNOME 3 Failed to Load*

Unfortunately GNOME 3 failed to start properly and started in the fallback mode.

This most likely means your system (graphics hardware or driver) is not capable of delivering the full GNOME 3 experience.

Try to turn on “Composite” in “/etc/X11/xorg.conf”.

Thank you, i remove the ‘gnome3 profile’ from the calculate layman.

I still like the gnome 2.