New installation.
whonix stable repository
whonixcheck ran through
apt-get update
apt-get purge virtualbox-guest-x11
http://postimg.org/image/i1h8n6193/
Problem as described above.
Virtualbox 5.0.6, W7x64
EDIT:
While at it; “Temporary disable Guest Additions” from https://www.whonix.org/wiki/VirtualBox_Guest_Additions#Installed_by_Default will also not work, as they will keep on getting loaded.
What you can do, is use fake install by making (for example) a vboxvideo.conf with install vboxvideo /bin/true. More here: KernelModuleBlacklisting - Debian Wiki