Dell Insprion Mini 10 won't connect to wireless network.

I have a Dell Inspiron Mini 10 that won’t accept the security key for my wireless.  It will connect to wireless routers without security, but it will not connect to networks with security.  I tried connecting to my network and I put in the correct key (I quadruple checked the key to make sure it was right) it won’t accept the key.  So I went to my son’s house and tried connecting to his wireless and still the same problem.  I tried the neighbor’s wireless same problem.  When I went to a couple of places where they did not have a secure encryption set up I could connect.  I can see the connection just fine with a great signal, my regular laptop is connected to my wireless as is my Ipod.  My kids come over and connect to the wireless just fine just not my Dell Mini 10. It is very frustrating; we have tried everything we can think of.  It acts like it can’t accept the key and encryption.  My security type is WPA2-Personal with Encryption  Type AES.