Fedora Core 2 NAT Router freezes when left running with Azurus running on a local machine.

Hi, I am new to Linux and have just set up a NAT Router with Fedora Core 2.
The computer is an old Packard Bell Club (Cyrex II 300.)

I have not yet setup any firewall stuff yet, just Masquerading. Everything
works fine and I have had up to 5 computers running on my LAN but when I
leave it all running over night my Linux box freezes and stops responding to
pings, also monitor goes off and nothing works.

This only happens when there is a moderate amount of traffic, e.g. Bit
Torrent (Azurrus to be exact.)

I have had the system up for days with Azurrus switched off. I have managed
to get the problem only once with Azureus switched off but I had to download
lots of files simultaneously and bombard my Linux Box with pings from the
LAN.

Incidentally Azureus is running on a Windows XP computer on the LAN not the
Linux Box.

I would have thought that the Linux computer would have been more than
capable of the traffic generated by one Bit Torrent Client.