Vaio VGN-T350P wireless connection problem

I'm trying to connect it to a 2wire router, but the "network" properties window keeps resetting the network key to to that of my previous router every time after I type in the new key and hit "ok."

another strange things. . .sometimes I get an intermittent connection and browsing works fine, but when I try to install McAfee software, I get a pop up saying I have no internet connection! (the same software I just downloaded over the same internet connection!).