Sorry for the lack on information.
This happens both at my house and my relatives house. We both have highspeed Internet and routers. I have the Apple Apple AirPort Extreme Base Station and my relatives have a Netgear of some kind. Both routers use WPA.
My Macbook Pro is about 13 months old. It has a 2.8 GHz Intel Core 2 Duo processor. I have 4 GB of RAM and a 500 GB hard drive. I am running OS X 10.6.4, Snow Leopard.
Another problem I have is obtaining an IP address. When I am using a wireless network which I have only used once or twice before, such as the WIFI at the airport or library, I have trouble obtaining an IP address. It usually takes several tries (turning my MBP's Airport on and off) before it goes from static IP to getting itself one (I hope my wording makes sense).
I would appreciate any help. Thank you