Ubuntu stuck in splash screen after using GPU for computing

Question

I am using a Lenovo Y50 laptop which has an intel integrated graphics and a gtx 960m, I have installed cuda 7.5 and I am using theano to compute stuff using nvidia gpu. After using gpu for computing (it doesn't seem to happen every time, my guess is that it only happens when too much gpu memory are taken) and shutdown, next time Ubuntu bootup will stuck in splash screen. If recovery mode is chosen, Ubuntu will have a login loop and can't get into the desktop. My temporary solution is to disable nvidia graphics by choosing UMA in BIOS, bootup Ubuntu again, shutdown and change the setting back to switchable graphics. I want to know if there's a more convenient way to solve this problem. Thanks in advance. My kernel version is 3.19.0-32-generic and the nvidia driver version is 352.39. Currently I am using 15.04 but this problem has happened before when I was using Ubuntu 14.04-3.

Answer 1

Install the latest official stable (short-lived branch) NVIDIA drivers 355.

But first uninstall every NVIDIA related software you had installed before.

Boot Ubuntu and when the login screen appears press Ctrl+Alt+F1.

Enter your user name and password and then execute:

sudo apt-get purge nvidia*  
sudo reboot

If you have had bumblebee installed the commands are:

sudo apt-get purge nvidia* bumblebee  
sudo reboot

Now install the new drivers and NVIDIA Optimus support.

When the login screen appears press Ctrl + Alt + F1.

Enter your user name and password and then execute:

sudo add-apt-repository ppa:graphics-drivers/ppa
sudo apt-get update
sudo apt-get install nvidia-355 nvidia-prime
sudo reboot  

Boot into BIOS and select "switchable graphics mode".