problems with networking...

[Michael Hawkins]

Sorry if this is sorta n00bish, but I have a problem that Google hasn't
answered for me yet...
I have a moderately-sized network that I am trying to run, with about 70 or
so machines on it.  The DHCP server (running FreeBSD 6.2, IPv4 address:
10.11.12.254, Subnet is 10.11.12.0/24) acts as a gateway server as well, and
has ipnat running for traffic routing.

So far, I have had no problems with ANY of the machines on this network
connecting, save one--my File server (running FreeBSD 6.2 as well, IPv4
address: 10.11.12.253).  For some reason, whenever I try to establish any
connection to ANY network address (on any protocol), it will only connect to
one address: 10.11.12.252 (and won't connect to anything when that machine
is off).
Here is a ping listing:
#ping 10.11.12.254
PING 10.11.12.254 (10.11.12.254): 56 data bytes
64 bytes from 10.11.12.252: icmp_seq=0 ttl=64 time=0.852 ms


...and it continues precisely in that manner until I stop it.

I have tried re-installing the OS on the file server, but with no change in
results.  I have removed the machine at 10.11.12.252 with the only change
being that the file-server can obtain NO connection to ANY IP address.

Any help would be appreciated.

Thanks,

Michael