Hi,(excuse my bad english)
A few days ago there appeared an exclamation mark in the wifi icon in the finder toolbar. I have a late 2009 macbook pro 10.8.2 and an airport base station. When I attach an ethernet cable i do have internet. When I run the diagnostics tool, it says to reset the router and cable modem. My two ipad's two iphone's imac and samsung wifi tv do have wireless internet. So there seems to be an arguement between my macbook and airport basestantion. Does anyone have a suggestion?