Hi, when changing the Concerto (VirtualBox, VMware etc) configuration try doing first a snapshot or clone the vm before doing the configuration changes, so you can fall backto it if something goes wrong with the new configuration.
TIPS
When staff disapears try to install those again:
Here you'll find some Concerto plugins & addons, remember to first backup your Concerto/Debian or vm before doing changes:
Concerto 2 Remote Video Plugin
Greetings Rodrigo