I suppose you have the wireless security set up correctly? Do they use any MAC address filtering?
If you right click on the wireless icon, do you show the network and signal strength? If you hover the mouse, does it show the security in place?
I suppose when you say you cleared down all the know networks, you know for sure you are looking at the correct one?
I can't check your post right now, but you do show you are on a private network?