Upgrading to 16.04

[Peter]

I found the package libqt5x11extras5 and installed it. I then 
reinstalled virtual box.  When I started VirtualBox it said I had 
outdated Extension Pack. Following the screen instructions the updated 
pack installed. The virtual box then failed to start complaining that:

RTR3initEx failed with rc=-192 (rc=-192)

The virtual box kernal modules do not match this version of VirtualBox. 
The installation of VirtualBox was apparently not succesful. Executing

'/sbin/vboxconfig'

may correct this. make sure you do not mix the OSE version and the PUEL 
version of VirtualBox.

where : supR3HardenedMainInitRuntime what:4

VERR_VM_DRIVER_VERSION_MISMATCH(-19132) - The installed support driver 
dosen't match the version of the user




Does this mean I have to recreate my Virtual machines using VirtualBox 5.1?

Why did 5.0 partially work?

Will running '/sbin/vbox config help or will it screw up my existing 
virtual machine?

Regards


Peter Goggin