Apple TV won't connect to Airport Express I just bought an Apple TV last night. I have it sitting directly underneath my Airport Express. I have 2 wifi connections on my Airport, one for my stuff and one for guests.

When I list the wifi connections in my Apple TV it sees both, however when I try to connect to either I get this message:


  There was a problem connecting to the network.
  
  Check your settings and try again. (-3906)


I tried with a bad password just to compare the difference and I get this message:


  There was a problem connecting to the network.
  
  The Wi-Fi password you entered is not correct. Try again. (-100)


So it can see it, and tell it is the correct password; but it will not connect.

My MBP, MPA, Android phone, Xbox, and guests' windows laptops have all connected to this airport without any problems.

It does work if I connect the Apple TV to the Airport via ethernet.
I have 2 apple tv’s.    One wouldn’t work anymore.     I went to Utilities, Airport Utilities and noticed there was a newer version available.   Once I installed the newer version my apple TV finally worked.   I don’t know if this will help anyone else, but it did the trick for me.