After having installed Ubuntu 14.10 freshly, I still have the same error that I already had in 14.04 and 12.04. The desktop sometimes just freezes. To use the desktop again I press Ctrl+Alt+F8 and then Ctrl+Alt+F7 to basically reload the desktop. I tried around a bit, installing Unity, KDE4, Gnome 3, Mate, Cinnamon, xfce, and I get the same error with all desktops. I still can continue my work, but it is truely annoying and I believe I am not the only one out there having this problem.

I already did some research, but have not found anything helpful.

My laptop is a Dell XPS with a Intel(R) Core(TM) i7-2630QM CPU and an NVIDIA GF116M [GeForce GT 555M/635M].

Is anybody familiar with this apparent bug?

[EDIT]:

The output of lspci -nnk | grep -iA2 VGA is:

00:02.0 VGA compatible controller [0300]: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0116] (rev 09)

        Subsystem: Dell Device [1028:0571]

        Kernel driver in use: i915

--

01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GF116M [GeForce GT 555M/635M] [10de:124d] (rev a1)

        Subsystem: Dell GeForce GT 555M [1028:0571]

        Kernel driver in use: nvidia