I can confirm that the bug is present for WEP, but not WPA in the backported 3.2.4-1 kernel for Squeeze. I haven't had the problem with the previous 3.2 kernel, it's only after the last update. dmesg gives deauthenticating for reason 3, as everyone here. It seems to be the recurring nohwcrypt problem. If I put "options ath9k nohwcrypt=1" in /etc/modprobe.d/ath9k the connection will work with WEP as well, though this produces some slight inconsistencies with the wireless signal. I'm connecting via ifupdown calling wpasupplicant's roaming profiles. dhclient was giving me no leases when I attempted to connect manually with iw and iwconfig to WEP.
$ apt-cache policy linux-image-3.2 linux-image-3.2.0-0.bpo.1-amd64: Installed: 3.2.4-1~bpo60+1 Candidate: 3.2.4-1~bpo60+1 Version table: *** 3.2.4-1~bpo60+1 0 100 ftp://ftp.at.debian.org/debian-backports/squeeze-backports/main amd64 Packages 100 /var/lib/dpkg/status cat /etc/network/interfaces ... allow-hotplug wlan0 iface wlan0 inet manual wpa-roam /etc/wpa_supplicant/wpa-roam.conf It's good you guys opened this bug, as I was attempting to do the same today and exim kept segfaulting on me :D