I know there are many posts like this, however none of the fixes I have found have worked.

I had the issue on 11.04, and after having no luck fixing it decided to try 12.04 however this has not fixed the problem. I'm using a Lenovo IdeaPad, the network card is a Atheros Communications AR9285.

edit add outputs:

sudo iwconfig
lo        no wireless extensions.

wlan0     IEEE 802.11bgn  ESSID:"NETGEAR-PLOW"  
          Mode:Managed  Frequency:2.437 GHz  Access Point: E0:91:F5:7D:1B:BA   
          Bit Rate=65 Mb/s   Tx-Power=15 dBm   
          Retry  long limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:on
          Link Quality=66/70  Signal level=-44 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:77  Invalid misc:63   Missed beacon:0

eth0      no wireless extensions.

lspci -nnk | grep -iA2 net
06:00.0 Network controller [0280]: Atheros Communications Inc. AR9285 Wireless Network Adapter (PCI-Express) [168c:002b] (rev 01)
    Subsystem: Lenovo Device [17aa:30a1]
    Kernel driver in use: ath9k
--
07:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8101E/RTL8102E PCI Express Fast Ethernet controller [10ec:8136] (rev 02)
    Subsystem: Lenovo Device [17aa:392e]
    Kernel driver in use: r8169

Thanks