installation problems with MN-720

Hello,

I have some problems with the installation of my mn-720
wireless card. The installtion works fine until I try to
login at any network. The MSBN-Utility displays the
available networks, I choose the one I want to connect
(excellent signal) and type the key into it. Then I get
the error message: "Unable to connect to the selected
network".

Has anyone else the same problems, or can give me an
advice?
I have the newest drivers installed and I am using Win XP
sp2.

thanks
Max