I have found when installing xlockmore on Tiny Core (3.8, 4.0.2, 4.2) it changes the permissions on /usr from root to staff. This is causing virtualbox to have problems.
I have tested this on a half dozen fresh installs on 3 different PC's. All of them have Xorg, and either OpenBox or FluxBox running.
Uninstalling xlockmore does change the permissions back to root on /usr