i have a samsung N130, a while ago the connection dropped suddenly and couldn't find any wi-fi connections. i'm using a D-link Usb dongle and i can find all the networks.
after trying everything, i was convinced that the Atheros chip is faulty, so i bought a new one, but it didn't work...so i tried my Atheros on an another netbook and it worked fine.
it can't be an OS problem since at the beginning of the problem i did a factory settings restore and tried Ubuntu, all of them had the same problem.
sometimes it is able to find near wi-fi networks only but won't connect.
so if anyone knows what's the problem i would really be thankful, it's very annoying!