Ok several things you need to look into. Make sure your firewall isn't affecting it. 2 some wireless phones disturb your signals from your router so make sure no one is talking on a phone. Make sure you are not to far away from your router. Try something different put your PS2 in the same room with your router (if you have a tv in there) if that works then you know your to far away. Try different things trial and error. Good luck.
The firewall is something all routers have. It is in stupid terms like a wall of fire it keeps things out, from your computer but sometimes they stop things that are ok. With out the firewall you are open to viruses but as long and you don't go to sites your not sopposed to

then you will be fine.