V 6.0.10 install on Ubuntu 16.04 broke Virtualbox entirely

[RadlyEel]

Today I tried to install 6.0.10 on my Ubuntu 16.04 host. The install itself seemed to run normally, but the first time I tried to Start a newly defined guest, I received this error:

RTR3InitEx failed with rc=-1912 (rc=-1912)
The VirtualBox kernel modules do not match this version of VirtualBox. The installation of VirtualBox was apparently not successful. Executing
'/sbin/vboxconfig'
may correct this. Make sure that you are not mixing builds of VirtualBox from different sources.
where: supR3HardenedMainInitRuntime what: 4 VERR_VM_DRIVER_VERSION_MISMATCH (-1912) - The installed support driver doesn't match the version of the user.

Running the suggested /sbin/vboxconfig accomplished nothing--I still get the error.
The installation procedure I followed is found here: https://www.virtualbox.org/wiki/Linux_Downloads

But what is REALLY disturbing is that after uninstalling 6.0.10 and re-installing 5.2, I get the same error. Which means I can't use Virtualbox any more on this host.

I'm willing to live with 5.2; can someone point me in the direction of getting either version to work?

[socratis]

Make sure that you are not mixing builds of VirtualBox from different sources.

That's your problem. It seems that you have installed both the official version from https://www.virtualbox.org/wiki/Linux_Downloads *and* the one from the Ubuntu repository. You need to completely remove/uninstall/delete/purge their version. Actually, purge everything VBox* and VirtualB* and try to install the official version again.