ok so a minute later all my virtual pcs are fucked :(
"Assertion failed: [!name.isNull()] at '/home/vbox/vbox-2.1.0/src/VBox/Main/NetworkAdapterImpl.cpp' (1068) in nsresult NetworkAdapter::loadSettings(const settings::Key&). Please contact the product vendor!."
woopee...seems the new virtual box breaks because if you have virtual machines that are set to use the tap interface, and you upgrade it cant convert the config for you.
So the simple solution is to goto your virtualbox config file eg
and delete everything between
so that something like this...
becomes something like this
save and restart virtual box and problem should be solved, you will just have to goto the config and select "host" and start the box.