Need computer help

[JET]

I know we have a few computer guru's on here. I am having an issue with trying to host a game. The game runs in java and one person hosts, while others play off their computer, through another server.

I went through, did the port forwarding thing for my router and that seems to work ok, but I end up getting errors about every 15 minutes. The port it uses is 3300 and when I use their checker is says this port is NOT open. I have done tons of research and tried a ton of things, but to no avail. I am running windows XP. I am sure there is just a setting somewhere that needs to be changed, I turned the firewall off in windows also. I have also asigned a permanent IP address to my computer and the port forwarding goes to it.

When I first started I couldn't host at all, but now it works good for 15-30 minutes, then I get the error. It would be greatly appreciated if anyone had a fix for it! Thanks.