ERROR: failed to create a session object! ERROR: code NS_ERROR_FACTORY_NOT_REGISTERED (0x80040154) - Class not registered (extended info not available) Most likely, the VirtualBox COM server is not running or failed to start.
The only changes where Virtualbox being bumped from 3.1.4 to 3.1.6 and a new version of the dependent graphics/png package. After much testing I determined that the problem was with the png update change but I couldn't figure out how to resolve it. I finally found a patch out and about that fixed this problem so I am posting more details here. The patch listed in that page is actually not a patch at all but rather a replacement makefile so i created a patch and posted instructions below.
Build the pached version
Patch, build, and install.
cd /usr/ports/emulators/virtualbox-ose sudo wget http://pynej.dnsalias.com/Shared/virtualbox-ose-3.1.6_2-1.patch sudo patch -p0 < virtualbox-ose-3.1.6_2-1.patch sudo portupgrade -f virtualbox-ose