After I upgraded to the latest version of VirtualBox, my virtual machines wouldn’t launch. The error reported did not seem very helpful — something like the following.
Failed to load VMMR0.r0 (VERR_SUPLIB_WORLD_WRITABLE). Unknown error creating VM (VERR_SUPLIB_WORLD_WRITABLE)
Googling around, I found an entry in the VirtualBox.org forums from February 2011 that suggested removing world-writeable permissions from the OS X main Applications folder (/Applications). I checked, and sure enough, that folder on my system was world-writeable.
Wow! That’s troubling! That folder ought not be world-writeable! So, was the VirtualBox installer responsible for making it world-writeable? I don’t know, but making that change at the command line as follows resolved the problem.
#sudo chmod o-w /Applications