FreeBSD's refusal to connect to the internet

[Colin Ryan]

I have a small network of three computers in my office here.  Two Windows
2000, and one FreeBSD 5.1.  It's the BSD box that's giving me problems.

My computers are connected to my modem via an ethernet switch. My modem is
set up as a DHCP server, and my computers are DHCP enabled.
When the input cable is disconnected from the modem (not the power, so it's
still assigning IP addresses to my LAN) my BSD box picks up a valid internal
IP address and subnet mask, it can ping and be pinged from all other
computers on the LAN.

However, when the input cable is connected to my modem, so it's connected to
the internet, my BSD box receives nothing.  When I do an ifconfig, it shows
NO IP address and NO subnet mask.

I tried "dhclient rl0" which didn't work, so I checked /var/log/messages and
was told "dhcp cannot bind to address; address already in use."  I then
tried manually assigning an IP and subnet mask, which didn't work either.

Getting FreeBSD online has been nothing but an ordeal, and I am about ready
to throw in the towel.  If anyone has any ideas, I would be very grateful
indeed.

Many thanks

Colin