Ok so I bought a used Macbook from my friend and it wont connect to my wi-fi service. It connects to My neighbors linksys perfectly, and I would use it all the time if it was always available. I have a Belkin Router. It connects to my wi-fi but that little icon that shows the signal strength just has a exclamation point, and says there's no internet access although, when I used to use my PC laptop to connect to my wi-fi it worked perfectly. Also when I go to school and try to connect to the wireless service there it connects perfectly and the signal strength is full, but when I try to open a page it just doesn't load. From reading a previous thread on this site I thought I might have to re-format my mac but Ive never done this and I am new to Mac's so I don't want to do something that I don't fully understand and might even end up giving me even more problems. Not to mention it works just fine when I connect it to my Ethernet port... Please Help!!