Here's a workaround for me: downgrade the kernel to 2.6.37.6 and everything's OK now.
my lspci output: 06:02.0 Ethernet controller: Atheros Communications Inc. AR2413 802.11bg NIC (rev 01) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/714300 Title: ath5k wireless fails to connect natty -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
