I'm having a horrible time with Unity 3D in Ubuntu 11.10 running in a VirtualBox VM in OS X. Such a hard time, in fact, that I'm about to give up and conclude that it simply isn't possible to use Ubuntu 3D in a configuration like this. The problem with is that windows simply do not render. I've found that killing Nautilus makes the problem go away, but that's really not much of a solution. I have installed the guest additions and am running the VM with 2048 MB RAM, 128 MB video memory, and have enabled 3D acceleration. I've tried all this on several Macintoshes, with no luck. Unity 2D, on the other hand, works fine across the board. Any advice or experience would be greatly appreciated.