Wifi won't connect

[Fire69]

Hey,

I just received my Edimax-dongle (it was recommended by KoenKK).
Plugged it in and started xbian-config through Programs in XBMC (not via SSH) and all available wifi-networks are displayed.
When I select my SSID, I am asked to input my key. After I do that, I get 'Connecting wlan to <my ssid> and after about 10 seconds it shows me the list with available wifi-networks again. When I close the list without selecting a network, it tries to connect to the next network in the list, which obviously fails...
I can do this 2 or 3 times, after that Xbian crashes and I'm stuck at a black screen.

Any ideas?

Thanks