I-net connection prob on network gateway???

I have just set up a network using a westell 6100 feeding 1 XP machine as a gateway.....then to a netgear gigabit switch....with 2 other XP machines on the switch using the gateway machine for I-net connection. The network works perfectly on all 3 machines and both of the machines behind the switch work perfectly on the I-net....HOWEVER...the gateway machine will connect to the I-net....but seems to be real particular about what sites it will load. Some sites it will load the home page and not load any other page on that site....some sites every page loads perfectly....some sites it just won't load at all. After several hours of searching I can't really come up with any fix on my own(plus I'm not real knowledgeable about DHCP, name resolution, DNS...yadda yadda)....so hence my post here looking for help.
Thanks
Mark

Thanks for the reply. I actually just got home from purchasing an 8 port switch. I had enough devices left that I would have used up the 5 port using a gateway machine. After 2 days of trying to figure this out I just bit the bullet and bought the 8 port and ran the westell into that and just put the other machines on the switch. seems to be working fine now. I was just trying to avoid buying the 8 port....

Thanks
Mark