On a computer with a NVIDIA GeForce GTS 250 graphics card running Ubuntu 14.04, I decided to update the installed driver from
nvidia-343. I did this:
$ sudo apt-get install nvidia-343
It installed the driver and then compiled and installed the kernel module. I rebooted the computer. I was able to login in the GUI, but got an empty desktop!
What kind of graphics driver problem allows graphics, but only hides the desktop elements in Unity? No idea. I dug through
/var/syslog, searched for
nvidia and found this:
NVRM: The NVIDIA GeForce GTS 250 GPU installed in this system is NVRM: supported through the NVIDIA 340.xx Legacy drivers. Please NVRM: visit http://www.nvidia.com/object/unix.html for more NVRM: information. The 343.22 NVIDIA driver will ignore NVRM: this GPU. Continuing probe... NVRM: ignoring the legacy GPU 0000:03:00.0
So, it turns out that the GTS 250 is no longer supported in the 343 version drivers and later. I removed this driver and reinstalled back 331 driver and got back my desktop.