This is beginning to look like the netbook wi-fi that isn't working.

I agree - especially since you can connect with a cable. You might try a USB or PC Card wireless adapter and see what happens. I would also run through your manual one more time. I am not too familiar with netbooks but most computers (especially portable computers) allow you to turn off integrated devices and features to conserve battery power. And wifi is often disabled as a security measure. Some have simple Fn key combos to quickly disable wifi. Or you may have to dig around in the BIOS or other menus.