I've recently updated to Ubuntu 15.04 and after installing the latest nvidia drivers (346.59) which worked on ubuntu 14.10 seems to have caused some trouble on boot.
All I get is the following when booting:
A purple screen for about a second and then
[0.514409] ACPI PPC Probe failed. Starting version 219
A black screen with a message of my monitor saying : No Signal detected.
I am using a GTX 970.