I have the exact same error as Uwe. Same hardware (Raspberry Pi, Fritz WLAN Stick 1.1) and Linux 3.6. I also tried with kernel versions 3.2 and 3.10 and I tried the driver on a x86 Debian Wheezy (Linux 3.2), but it has the same effect.

Uwe, have you been able to fix it?

Thanks for your good work. Regards.