I've been trying to copy a Proxmox container based on the Ubuntu Precise Standard template to a VirtualBox VM. I am now stuck at a point where my new Ubuntu/VirtualBox VM hangs after the message "Running /scripts/init-bottom ... done" during boot.

• I started by installing Ubuntu Server 12.04.4 LTS on a VirtualBox VM. Ubuntu Server 12.04.4 LTS was the closest "official" Ubuntu ISO to the Proxmox container OS I could find.

• I installed all updates on both the Proxmox container and on the VirtualBox VM.
  The idea was to get same version kernal running on the ProxMox container and VirtualBox VM.
  sudo apt-get update ; sudo apt-get upgrade ; sudo apt-get dist-upgrade
  sudo reboot

• rsync the entire proxmox container to a temporary directory in the VirtualBox VM:
  cd /
  mkdir /tmp/backup
  rsync -e ssh -av --exclude={/dev,/proc,/sys,/tmp,/run,/mnt,/media,/lost+found,/boot,/selinux} root@my_proxmox_container_hostname:/ /tmp/backup

• Shut down the virtual machine, and boot the VM with a bootable linux image.
  I used the Desktop image of Ubuntu 12.04 LTS, ubuntu-12.04.4-desktop-i386.iso

• Drop to a root prompt.

• Mount the VM root filesystem:
  sudo mount /dev/sda1 /mnt

• Remove files from most of /mnt
  cd /mnt
  sudo rm -rf bin etc home lib opt sbin root usr var

• Move all of the files from /mnt/backup into /mnt
  sudo mv /mnt/tmp/backup/* /mnt

• Rebooted system. For me, at this point the system freezes after starting, after the message:
  Running /scripts/init-bottom ... done

I've tried reinstalling GRUB and all manner of other thing. I am almost ready to give up.