Comment 18 for bug 721449

I'm also experiencing the same problem with the following hardware

$sudo lspci -v
03:00.0 Network controller: Atheros Communications Inc. AR5008 Wireless Network Adapter (rev 01)
 Subsystem: D-Link System Inc Device 3a70
 Flags: bus master, fast devsel, latency 0, IRQ 16
 Memory at fdcf0000 (64-bit, non-prefetchable) [size=64K]
 Capabilities: [40] Power Management version 2
 Capabilities: [50] MSI: Enable- Count=1/1 Maskable- 64bit-
 Capabilities: [60] Express Legacy Endpoint, MSI 00
 Capabilities: [90] MSI-X: Enable- Count=1 Masked-
 Capabilities: [100] Advanced Error Reporting
 Capabilities: [140] Virtual Channel
 Kernel driver in use: ath9k
 Kernel modules: ath9k

The following workaround originally found here http://aptosid.com/index.php?name=PNphpBB2&file=viewtopic&p=6499 seems to work for me as a workaround.

create the file /etc/modprobe.d/ath9k.conf and add

options ath9k nohwcrypt=1

Save and reload the module or reboot.