Problems after connecting ad-hoc WLAN

I have problems with ad-hoc networks. I connect using networkmanager-kde4. After connection is established some time all works normally. After some time (2-minutes or bit more) connection hangs. Keyboard becames unusable too. At proccesses list I see hanging firefox, events0 and kind of wlan and nm processes…

When I connect to managed networks all works perfectly.

I’m on KDE-4 and OpenSuse 11.1.

Any ideas? Thanks!