Chosen Solution
My macbook finds a wireless signal and the airport bars usually go to full. After a few seconds it seems to be searching again and comes up with that dreaded excaimation mark (!) saying that there is not wireless connection. Plenty of networks are available with full strength when I search for them and I have access to them. The last network I got on was a weak signaled Linksey network and that pooped out after about 10 min.
First I would check out my software by hooking up via a hardwired ethernet connection. If that works OK, then look at replacing the AirPort card. For the correct part and installation guide, please give us the last three figures of your serial number (located in the battery compartment on most MacBooks).
