Today, I was pleased to see VirtualBox 4.1 release announcement on OTN. New features sounded encouraging, especially the support for Linux Unity and GNOME 3 desktops. So, I decided to give it a try with installation of Ubuntu 11.04 x64 guest. I tried installing guest from ISO image several times and was always blocked at time zone selection. Installer simply hanged.
Google returned numerous reported incidents, I tried out several workarounds, unsuccessfully, until I found someone who said that the only thing that worked for him was when he removed NIC from virtual machine. Bingo! After I completely removed NIC from VM guest machine I was able to finish Ubuntu 11.04 installation (make sure you check 3D support for video!). Then I installed VirtualBox guest additions as usual, then I made a shutdown. I added NIC back to VM guest and I was able to boot and login with Unity interface. I hope this note will spare someone troubleshooting Ubuntu 11.04 installation on VirtualBox 4.1.