Have problem accessing certain remote computers

First of all, I'm connected to another computer with a crossover cable to the internet.

I use p2p program such as Soulseek and here's the problem I ran through.

I am unable to connect to certain computers. Even if I disable all firewalls from the other computer.

Now if I directly connect myself to the cable connection then I have no problems.

So my question is.. why does this happen? How does me routing through another comp make any difference and is there ANY ways I could fix this?

Would a router fix this?

Thanks for reading :D


Darv