Not sure if this will help but at one point my VB installation vanished unexpectedly after an update/kernel change........ or something, however under More Applications, Emulators, there was the option to "Get Oracle Virtual Box" which I duly clicked, it downloaded and all was well.
Yup - that's normal.
After a major update (or when a new version of Virtualbox comes out) the Virtualbox app needs to be reinstalled using
Getvirtualbox BUT it doesn't affect any of the VM's or VDI's - they stay in place and can be used as normal.
The reason this is done is to have the version of Virtualbox which has access to USB, therefore the Tex and some community members created the
Getvirtualbox script which downloads and installs it.
Edit: I
believe when Oracle took over Virtualbox they no longer created a PCLinuxOS Virtualbox rpm whereas when Sun had control they used to provide one (which is why this route is now taken.