When I view available wireless networks I am shown two unsecure networks and several secure (sometimes WPA) networks. Previously my laptop would connect to the unsecure networks with no problem but now it tries to acquire a network address from the secure ones only and then comes back as not connected.
I can't get it to try and acquire an address from the unsecure networks and so cannot get online. Even if I mannually select one and try and connect it does not work.
Unsecure doesn't mean that you can connect to it. An unsecure network is merely unencrypted (the data being transferred between the computer and the router wirelessly is not encrypted). However, there are other ways of making sure people cannot connect to a wireless network.
My neighbour has an unsecured wireless network with MAC address filtering which means that only computers with approved MAC addresses can access it.
It may be the case that the network you are trying to access has this filter on. Speak to the administrator to see about adding your network card MAC address to the list. If it is your home network, try resetting the router back to factory settings.