- The version of VirtualBox you are using, and whether you have installed the Guest Additions (in the guest). virtbox v. 4.3.30 r.101610. Host ubuntu server. Guest add : No.
- Host & Guest make and version including 32 or 64 bit, and the amount of memory available to both. vers. 64bits. Ram 8Go. 1024Mb for guest.
Based on your screen shot it looks like your host is Windows 7 and not Ubuntu Server.
Attach the VBox.log…
Right click the VM in the VirtualBoxGUI. Select "Show Log". Save "VBox.log" to a file. Compress that file and attach it to a message here. Make sure the VM is fully shut down beforehand.
OSX, Linux and Windows Hosts & Guests
There are three groups of people. Those that can count and those that can't.
AFAIK your problem has nothing to do with updating VirtualBox. It's a typical symptom of display configuration being messed up, e.g. if the VM is abruptly closed while minimized. It has happened many times before, and been discussed here. If you search then you might find some examples.