Very strange problem with WLan caused by openchrome????

Hello to all!

I’ve got a very strange problem with my Amilo K7610GW.
First I had much problems getting a running driver for my onboard graphiks card (VIA K8M800). I tried with openchrome, vesa, and unichrome. Openchrome is the only wich works without problems on my Laptop. I have 2 WLan-Areas. The one ist from Fritz!Box 7270 and the second from TP-Link Wireless Access Point TL-WA-500G. My Wlan-device is ( Complex Wireless 802.11 b/g Mini PCI Adapter, Rev A1 [WLM54G] from Atheros (AR2413 802.11bg NIC)).
Wlan is configured by KNetworkmanager.

If I use Openchrome driver Wlan with TP-Link works fine. WLan with Fritz!Box connects error-free but there is no Data transfer possible. Ping Fritz!Box gives the following massages: Destination Host unreachable and sometimes a kind of buffer error.
With vesa or unichrome driver, both Wlan work without any problems!
Starting/Stopping Firewall doesn’t matter.
I also used xorg.conf of unichrome and set driver to “openchrome”.
But this doesn’t have any positive effect.
I also shut down KNetworkmanager and configured Fritz-Wlan with yast.But there ist the same problem too!
KNetworkmanager seems not to be the reason.

Does somebody have an Idea, what I could do to run Wlan with Fritz!Box and openchrome?