Thank you also. I thought I was looking at a downgrade from Mojave to High Sierra but found that the VMWare option had become deselected/unticked in my privacy settings after I had upgraded my Macbook Pro (host) to Mojave. For anyone else with this issue my set-up is
* Macbook Pro late 2014 (now running Mojave)
* Fusion 10.3.1
* 2 x VM's (1 x High Sierra and 1 x Windows 10) ... never at the same time
Symptom was that either VM would start OK (High Sierra would present a grey screen with Admin and Guest login options and the Windows 10 VM would present the only the start screen with no login option.) The mouse would move around OK but wouldn't do anything when I clicked around nor use the keyboard.
I made the Security/Privacy changes as per this thread and now I'm back to work