Failed to load VMMR0.r0 (VERR_SUPLIB_OWNER_NOT_ROOT)
In most cases the error above is useful, it generally means /usr or /usb/lib or /usr/lib/virtualbox is not owned by root and this is the cause of the error.
Solution
sudo chown root.root /usr/lib........
Failed to open a session for the virtual machine XP.
Failed to launch Remote Desktop Extension server (Unknown Status 0x80004005).
Disabled remote display:
Failed to load VMMR0.r0 (VERR_SUPLIB_OWNER_NOT_ROOT).
solution
chown root.root /usr/lib/........