Network Problems

I am getting the following error when I use any type of networked
program (telnet, ssh, etc.):

socket: Address family not supported by protocol family

This box was working fine until I rebooted it. Would this happen if I
re-used an address that another device is using? I am not sure that
this is happening but it is possible due to the way we assign IP
addresses.

Any other ideas?

…Stephen