What security scheme?
WEP and WPA2 are known to work. I think I've seen reparts that older WPA doesn't.
As for outsiders... Does your access point support MAC filtering? And suppressing the SSID broadcast?
I'm configured for WEP, MAC filtering to only my devices, and no SSID broadcast. I'll probably change to WPA2 since only my old laptop card seems to not work withWPA* but all else does, and even in the same room the laptop has problems (wire works much better).
A while back I was trying to connect my nook to a new router, I have no experience with wireless setups and routers. I got it to connect to the router, not my network, by using the 'preshared key' that was listed in the router info. Have you tried that? It was a dlink router, the key might be called something else on a different brand.
The odd thing for me was that the nook connected fine but I could not get my computer to work with the router. I gave up on it entirely and got a wireless gateway from AT&T, since I already use them for phone and internet. The gateway is terrific, my computer connects to it with an ethernet cable and the wireless is always on for the nook.
I had the same problem. I unplugged wifi plug counted to 30 plugged back in and it connected now.