Gnome session hangs on splash screen

[martin benavides]

For some reason gnome hangs at startup, the ubuntu splash screen appears
and the mouse works but it gets stalled. This happen when i updated some
packages yesterday then reboted and gnome wont' run, a workarround is
to enter a terminal and kill bonobo-activation, after that gnome starts
but warns about themes not working properly.

Is there a fix for this? or should i reinstall?