i am also dealing with the same problem 
I decided to build a freenas server on a P4@2.4GHz, 4x256Mb Ram and, for now, just one 2Tb HDD.
The hardware was tested for about a week running XP. No problems.
Server is connected to a Pirelli VoIP router with a patch cable and my main PC is also connected to the router, but with a crossover cable.
Everything went smoothly: installation on the 4Gb CF card was a breeze, boots up, no errors or warnings (not absolutely certain about that, things scroll too fast; where are the logs located, really?), acquires an IP via DHCP. I thought everything was ok, since my first test was to ping to and from the server and had no packages lost whatsoever.
However, I can not access the webGUI.
I used:
1) Opera, Chrome, Firefox and IE on my Vista ultimate laptop
2) Chrome from my Win 7 ultimate desktop
3) Opera, Opera mini and Chrome from my Meego/Linux tablet pc.
I tried:
1) Manually setting up network attributes
2) Changed IP to the one forwarded through port 80 by the NAT virtual server
3) Trying different combinations with the DDR Ram modules (in case some module was dead)
4) Unhooked my main pc from the router
5) Tried connecting the server via the crossover cable
Now, for some obscure reason, number 5 worked...once! And this baffles me even more. Indeed, once I unhooked my main PC and used the crossover to connect the server to the router, I was able to access the webgui via opera on my laptop. I turned things off, went for a midday nap and it never worked again. What's going on here guys? Any suggestions?
Showbox| Kodi | Lucky Patcher|