FreeBSD install fails on VirtualBox [FIXED]
A known issue, faced by many, who at first usually blame themselves or the installation image, is that the installation process sort of ends of its own accord when extracting the archives, and after a reboot, it displays an error, the nature of which suggests that it failed to find files to boot.
Anyways, try enabling IO APIC from the system settings page. Might do the trick.