I have been using iMac 21.5 and it was running on Snow Leopard but I have recently upgraded it to OS X Lion. Since then it is not able to connect to the network through wifi. I was not having any such issues with it previously and everything was working fine. I don’t know what has gone wrong with it after the update. When I am trying to connect to the network then it is giving me a "Connection Timeout Error". I don’t think that there is anything wrong with the network as other devices are able to connect to the same without any issues. I just wanted to know what might be the possible cause of this issue. What can I do to fix the same??