Comment désactiver l'horloge dans virtualbox.
Ce thread en parle..
La solution, apparemment içi :
Sorry to resurrect such an old thread, but it's the #1 Google search result for the topic.

This can now be done using VBoxManage utility. It's a command-line tool, which is available in the Virtualbox install folder in Windows or in ~/Library/Virtualbox on Mac.

Turn off time syncing:
vboxmanage setextradata [VMname] "VBoxInternal/Devices/VMMDev/0/Config/GetHostTimeDisabled" "1"

Turn it back on:
vboxmanage setextradata [VMname] "VBoxInternal/Devices/VMMDev/0/Config/GetHostTimeDisabled" "0"

note: [VMname] is the name of your virtual machine.

Hope this helps someone!