Another problem with Fedora Core 4

Hi.
Some of you already know what I'm doing already. I'm doing an IPv6 only
network for a project for college. Our DHCP/DNS server is on Debian and its
address is 2001::1, our other server that will do something someday is on
Windows 2003 Server and its address is 2001::2.
 So last week our client on Fedora Core 4 could ping6 without any problem
our servers and the other client. Then it just stopped working.
eth0 on FC4 has no IPv4 address and the Network GUI thingie tells me the
interface is down. I tried putting him a static IPv4 address just to have an
"up" interface, it works but I still can't ping6 my servers. I get an error
saying :

> connect: Network is unreachable

 The eth0 interface on FC4 gets an address from our DHCP server, Dibbler,
too that's why I really don't know what's going on. Our other client has no
problem pinging the servers.
 Another problem is that when my FC4 client was working, DNS would work too.
I could ping6 debiansrv and win2k3srv but I couldn't ping any servers on
Windows XP. I've heard that Windows XP doesn't like domain names without any
. in them, but I've tried putting one and it's still not working. I'm using
dnsmasq, because Bind really looks complicated with IPv6.
 Thanks a lot for your help, I really appreciate it.