Installation problem

[Terrence Wilson]

I'm trying to install FreeBSD as part of a dual boot config on a hard 
disk which already contains Windows XP. I have created a partition for 
FreeBSD. My problem comes once I "commit" to the installation of 
FreeBSD. I get the following message, after which installation aborts: 
"Unable to find device node for /dev/ad4s2b in /dev! The creation of 
filesystems will be aborted." What am I doing wrong?