Hosting netgame problems

Here is my problem; I host a game and it shows up on the server with the correct port. Most of the time my game shows up for a minute and then it disappears. I have hosted about 2 successful netgames with the same router.

I have a static ip, for my computer, but not the router. I have tried to have a static ip for my router; it worked for a while, but I had to reset the router to its default configuration to make it work again. I have a Linksys WRT54G.

So, is there any way to have it consistently host my netgames, so that it will stay on? Or does the Linksys WRT54G have a problem with forwarding ports?

Finnaly! Someone has the same problem as me!!! .....x(
Sorry about that!Its just its really annoying on launching a net game.