FreeBSD 9.0 on VirtualBox 4.1.8

[Robert Simmons]

I encountered a problem installing FreeBSD 9.0-RELEASE on VirtualBox
4.1.8, and I wanted to share my fix for it, so it can be added to the
FreeBSD wiki and Handbook if appropriate.

Using the default settings of VirtualBox, the following error occurs
during boot from the iso image:
http://i.imgur.com/kO93X.png

I'm using Kubuntu 11.10, and I installed VirtualBox from the official PPA:
deb http://download.virtualbox.org/virtualbox/debian oneiric contrib

The FreeBSD ISO that I used was "FreeBSD-9.0-RELEASE-amd64-dvd1.iso"

The following checkbox needs to be checked in settings to be able to
boot FreeBSD:
Settings > System > Motherboard > Enable IO APIC

With that set, everything works great:
http://i.imgur.com/Kdyom.png