I tried to install 1.2.3 onto an old Pentium 4 1.6 but when it got to the part where it was attempting to FDISK the drive the bios was sending the correct head count and it kept saying the only valid number is from 5 - 1024 but free bsd wanted the number to be 5003. Changing this number did nothing it still failed with the same error. I skipped this part but without a format the boot-loader did not load.
Using the original HP machine I did a clean install (I even chose the single processor option this time). No packages. I have the exact same result. Unfortunately right now I do not have another machine to install on.
Since both machines have the same motherboard and different NIC cards, it comes down to this specific motherboard. It is the HP XW4300 using Intel 955X chipset dual core Intel Pentium D 840. I think I have checked the different hardware possibilities sufficient with these 2 separate computers to say either the software is not working (not likely) or the drivers are not playing nice with this motherboard.
I do not know enough about Free BSD to install different drivers and try to make it work.