Windows 7 x64 fails to install on Virtual Box

I was recently installing a 64-bit version of Windows 7 to do some testing and the Virtual Box image would fail with an error after 10 seconds of booting from the install CD. The error as seen in the image below had the following details:

• Status: 0xc0000225
• Info: An unexpected error has occurred.

Every time I pushed enter it would just return to this same error page. It turns out to use the 64-bit version of Windows 7 you have to enable the "IO APIC" option in the Systems settings menu.

Once you select this option, attempt the installation again and you should be allowed to successfully install your OS and have a 64-bit virtual machine. I have not tested this with other OS's but I would guess this needs to be done for all 64-bit operating systems.