help with debugging internal network problem

Hi all,

last night I lost power to my RH7.1 box and my windows box...

RH7.1 acts as gateway/router/firewall...
windows box is part of my private network...

when I brought them up again, I had somehow lost my network connection
between win box & RH box...

the first weird thing that I found was that my RH internal NIC had the
same IP as my external IP! Weird! After I changed it back to
192.168.1.1, I was still unable to ping my win box, 192.168.1.2, or vice
versa;

I also tried a tcpdump trace on my internal device, eth0, during the
pinging; nothing to report when pinging from the win box, but the
following when pinging from RH:

arp who-has <windows_box_name> tell <RH_box_name>

any suggestions on how to diagnose further? does it sound like possible
NIC/cable problems?

thanks in advance,

Kevin