network problem with connecting out side the lan

[Vulpes Velox]

After I have had a lot of in/out bound traffic going through my NAT box, I begin
having problems with any getting any thing in or out. This problem only seems to
come up after I have been using p2p or listening to streaming music for awhile.
I can easily ping any box on my LAN with out any problems. Some times it will last just a short while, others it will last several minutes.

The setup looks a little like this...

192.168.0.1 <natd/defualt>
fxp0: cable
fxp1: LAN
OS: FreeBSD 4.6.2-RELEASE

192.168.0.2 <server/archive/whatever>
This box has a cheap realtek ethernet card in it... iirc a 8129.
OS: 4.8-stable/current(forget which)

192.168.0.3 <gfx box>
dc: 
OS 4.7-release

192.168.0.4 <gaming box>
/me forgets what network card it has in it
OS: win98

Then I have a Zonet 10/100 switch.