I was able to reproduce this with VirtualBox 4.3.6 on my Macbook Pro, here's the steps exactly as I did them.
Go through all the steps and just choose the defaults, the only thing I did different was choose 2GB of RAM and I upped the video RAM to 128MB as well as checked 3D acceleration.
Start VB and choose the Ubuntu ISO
Go through, choose time zone, keyboard and login and wait for install to finish. Once finished, reboot the VM.
Once rebooted, login, open a terminal and do an update