This seems to happen in many different drivers but it happened more often in newer versions such as 530 vs 525.
Then nvidia-modeset goes to 100%
There are many reports of this appearing since driver 4.70 and I can confirm I've seen this in various machines.
https://forums.de........
It may appear to be an Xorg or lightdm/gdm/mdm error but in reality for many users with this issue, it's a driver conflict and issue. I had a system that had two GPUs, an Intel and Nvidia GPU.
The only thing that got it working was to remove the nouveau driver and blacklist it so it never came back, then the Intel GPU works fine without these issues.
Solution
sudo rmmod nouveau
add nouveau/other driver to blacklist
edit th........
When running cudaminer once it tries to initialize the card the entire screen freezes. The computer itself is still running but the Xorg is done for, you cannot even switch to another console window and must reboot (even an mdm or Xorg restart does not help).
At first cudaminer will give you these errors:
stratrum_recv_line failed
...retry after 15 seconds
GPU #0: Geforce 210 with compute ca........