black macbook running 10.5.8 having weird wifi issues..

Hello Everybody,

So my MacBook is having strange wifi issues. We recently got wifi in my apartment, and everything was working fine. I could connect to the internet via airport anywhere in the house for about a week or so, but suddenly I can no longer connect to our home network unless I'm right next to the router. Throughout the house airport shows that I have full signal strength and an IP address, but I'm only able to connect to the internet literally if I'm ~2ft away from the router. Strangely, my phone is able to connect to the wifi anywhere in the apartment, as well as all of my roommates electronic devices. One of them has a mac (way newer than mine) and she isn't having any problems. I have tried the following remedies:

1. turning on/off computer and router

2. 'deleting' and reinstalling airport

3. deleting system preferences

For y'alls reference, I have an Arris TG862 router : http://www.arrisi.com/products/product.asp?id=79

Any suggestions as to how to remedy this issue would be greatly appreciated!!!

Cheers,

D