Oracle say that that the latest version -“VirtualBox 4.1mproves stability and fixes regressions” – whatever you take that phrase to mean. If you want to give it a whirl, take a gander over to the Virtualbox site and download it.
Virtual box has improved a quite a bit since it first came out. I am now going to use it for trying out doobry versions of Linux. There is an awful risk of messing up your working environment otherwise. With it all inside a virtual machine, a least you can just drag the disk image to the Trash!