The problem is in the guest-additions, the video driver needs to be updated for the recent ABI change in X (9 -> 10):
[ 5.900] (EE) module ABI major version (9) doesn't match the server's version (10) [ 5.900] (II) UnloadModule: "vboxvideo" [ 5.900] (II) Unloading vboxvideo [ 5.901] (EE) Failed to load module "vboxvideo" (module requirement mismatch, 0) ** Changed in: virtualbox-ose (Ubuntu) Status: Confirmed => Invalid ** Changed in: virtualbox-guest-additions (Ubuntu) Importance: Undecided => High ** Changed in: virtualbox-guest-additions (Ubuntu) Status: Confirmed => Triaged -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/738330 Title: Today's Natty update means no guest additions in virtualbox -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs