[supernoob]VB can't boot from its presets

[sorry_I_m_stupid]

Hi everyone, sorry if it' may seems naive

I'm on an Intel Core i5, Win7 64bit, using VB 4.3 to run Ubuntu or Kali as guests.
When I launch the vm VB displays this message:

This kernel requires an x86-64 CPU, but only detected a i686 CPU.
Unable to boot - please use a kernel appropriate for your CPU.

I tried also to download the image of Kali for VB from it's official site; It starts the Kali menu to choose what to boot (Llive, with persistence, intallation, grphical installation, and so on) but at the end non of this options works (black screen with blinking cursor).

Please can you help me? I just don't know from what to start, I think I've done everything straightforward, nothing strange, but it doesn't work.

[BillG]

You have two choices. Download and install 32-bit version of the OS in the vm or enable hardware virtualization on the host.

viewtopic.php?f=1&t=62339