FreeBSD ISPConfig 2 install on FreeBSD 5.1
This post is a bit late but we have tried installing ISPConfig on FreeBSD 7.X with no success. It looks like the Apache 1.3 that ISPConfig uses has some issues with FreeBSD. If you want ISPConfig to work then you can install FreeBSD 5.1 and it should work with a few slight modifications.
Hope this helps