Airport won't connect

I have an iMac, about 3 weeks now. I connect to the internet via linksys router. When I first got the computer 3 weeks ago airport would not connect through my network, although I put in the correct WEP password and my laptop was connecting fine. I could also connect to a neighbor's unsecured network (which I am using now to write this). I called linksys and the tech told me that I needed to put a dollar sign ($) before the password, which I did and I was able to connect fine. Yesterday morning when the computer woke up from sleep I could no longer connect through my network, tried inserting the WEP password again with and without the $, but can no longer connect through my network, only through the neighbors. Anybody have any solutions? Clearly the linksys/internet works, but my Mac won't acknowledge my correct WEP passwrod.