I was installing Oracle VirtualBox 5.0 as per http://www.if-not-true-then-false.com/2010/install-virtualbox-with-yum-on-fedora-centos-red-hat-rhel/.

I ran into the following issue.

Stopping VirtualBox kernel modules [ OK ]
Uninstalling old VirtualBox DKMS kernel modulesError! There are no instances of module: vboxhost
5.0.4 located in the DKMS tree. [ OK ]
Trying to register the VirtualBox kernel modules using DKMS[ OK ]
Starting VirtualBox kernel modules [FAILED]
(modprobe vboxdrv failed. Please use ‘dmesg’ to find out why)

It took me ages to find the solution but it turned out to be that changing the kernel is not allowed by secure boot. Stands to reason I guess but it would have been nice if there was more information about that. I disabled secure boot and it works. Not ideal.