When I start my computer the boot process is fine, until the login screen should show up. Instead of this, I only see a black screen.
I must switch to console (Ctrl Alt F1), then kill the system graphics server by command:
sudo kill -9 `pidof X`
After this, the login screen shows up. I'm not using any graphics card, just the Intel HD 4000 core i7 processor.
How can I fix this problem? Thanks.