Ok ... so I've been trying in vain to get sound out of my GT520 HDMI port. The latest attempt was to try the 290.10 drivers from NVidia directly. So I removed the current drivers, killed lightdm (gracefully) and installed.
Boom ... no graphical interface at all. Got a message about API conflict where I had driver 290 and the kernel had 285. Ok , so I uninstalled the new drivers.
The GUI comes back, but before it logs in, I have to click a button 3 times. This button and (I think) error message are *tiny*. I have no idea what they say. Only that they're a button, and I click it three times, then GUI.
But no unity. It loads my desktop background, and apparently loads Nautilus, and that's it. I have a file manager.
I'm not sure how to get past this. The only thing I see is in dmesg where it say:
PID: 1002, com: Xorg Tainted: P C 3.0.0-15-generic #26-Ubuntu
Then it dumps a "Call Trace" about nvidia (lots of repetitiveness and some memory addresses, but I don't see anything useful).
Not sure how to get out of this state. I thought, maybe uninstall all the nvidia packages? All that's left is nvidia-common, nvidia-current, nvidia-current-updates, nvidia-settings, and nvidia-settings-updates ... which would seem harmless enough.