Hi geiff, and welcome to the VMware Communities!
There's a known problem with the combination of VMware Fusion 5 and the most recent Apple Macs. You should be able to work around the problem by disabling 3D graphics support: With your VM powered off, go into Virtual Machine> Settings, then choose Display, and turn off the Accelerate 3D Graphics option. Then close the Settings window and power on your VM.
There is an update in the works that will get 3D graphics working again, although I can't say when it will be released. Hopefully the above workaround will get you through until the fix arrives.
Cheers,
--
Darius