Creating a 64 bit Ubuntu VM on Virtual Box results in the following error:
VT-x/AMD-V hardware acceleration has been enabled, but is not operational. Your 64-bit guest will fail to detect a 64-bit CPU and will not be able to boot.
Please ensure that you have enabled VT-x/AMD-V properly in the BIOS of your host computer.
To fix this problem, first verify that the host machine processor supports VT-x. You can do this with securable.
In my case, the host machine is using Intel I7 2600, which comes with VT-x (hardware virtualization support).
Alternately, to confirm what VirtualBox sees, select the machine, then click the “Machine” menu, select “Show Log.” Save the log and search for “VT”.
00:00:00.762 HWACCM: No VT-x or AMD-V CPU extension found. Reason VERR_VMX_MSR_LOCKED_OR_DISABLED
If it virtualization support is available, but turned off in the BIOS, you will need to reboot and enable it in the BIOS settings. Once it is on, you need to fully power off the machine and restart. More information is available here. The VT-X setting is only available through the “Advanced” section of EFI.