openSUSE 11.4 won't boot after installing in Virtual Box

Hi
I’m having some weird problem with openSUSE 11.4 on Virtual Box 4.1.8. I’ve been using openSUSE 11.4 x86 with Gnome desktop & Virtual Box for quire some time now without any problems. A little while ago, while running Virtual Box 4.1.4 I urgently needed some free space so I deleted the installation (bad move, I should have made a backup). Shortly after I tried to reinstall and everything went OK 'till it reached the first boot after installation where it hangs with a black screen and a loading cursor. That sounded like a VGA problem to me and it was. I keep 3D acceleration enabled and I even (used to keep Compiz Fusion on). Now I know it’s not something you expect from a virtual machine but it keeps everything smooth. Now I was able to boot & login after I disabled the 3D acceleration but everything works as if I installed some ancient OS on a modern system: cursor leaves trials behind it and windows & apps image remains “printed” on the desktop or on top of other windows. Any ideas ow to get 3D back?
BTW, I never had enough time to dig into Linux too much so I guess I am kinda newbie.

Generally you need to install the addon drivers again if you change VBox version. Did you do that??

Done that, even if I never had to do it before since it worked out of the box. But it didn’t work.