Installed the latest stable kernel using yum. On booting, a few seconds after the splash screen, I get a solitary blinking cursor. Rebooting with the previous version (3.18.8-201) works fine. Video is an Nvidia GT630 using the kmod-nvidia driver.
for me, I always have to run 'yum update' twice. The first time, I get the new kernel from fedora, then I need to reboot and do 'yum update' again for the nvidia driver. Sometimes, the graphical interface does not start after the reboot. Can you switch to a terminal window with Ctrl+Alt+F#? If so, try to log as root, do yum update and reboot. Frédéric