I just downloaded and installed Oracle VM Virtualbox version 4.3. My host machine is a 64bit Ubuntu box as well, version 14.0.4
I used this page:https://www.virtualbox.org/wiki/Linux_Downloads and selected the Ubuntu 13.0.4 AMD64 option.
In creating a new VM, I've noticed that I don't have 64bit Ubuntu as an option in the list of Linux machines.
Can someone tell me where I've gone wrong?
Thanks
I had the same problem some days ago, and the steps that I followed to solve it are the next ones:
Hope it helps