kernel-core-3.18.9-200.fc21.x86_64 fails to boot

[Frédéric Bron]

> 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