I just bought a macbook air. everything works fine except the wifi. I have another pc connected to same wifi network. Each of them connects with no problem when the other is not connected. But everytime I connect both to the same wifi at the same time, the connection works for few seconds then all connection down. I have to reboot the modem but doesn't solve the problem. I assume it is my MBA's problem. I have no problem connecting my other devices like iphone and ipad to wifi when my pc is connecting too. Any idea why is this happening?