Wireless unstable with an Atheros AR9285

Question

I have a Asus eee PC 1001PX running ubuntu 12.04. Everything works well but the wifi is unstable. When I boot the wifi works fine, but after about 5-10 min it gets slow, disconnects etc and the computer starts to run slowly. The it is ok after reboot, for about 5-10 min.

Any ideas? I have tried everything I have found with google but nothing works. I have tried a few different wifi routers and it is always the same.

sudo lshw -class network


  *-network               
       description: Wireless interface
       product: AR9285 Wireless Network Adapter (PCI-Express)
       vendor: Atheros Communications Inc.
       physical id: 0
       bus info: pci@0000:02:00.0
       logical name: wlan0
       version: 01
       serial: 48:5d:60:7d:b8:66
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
       configuration: broadcast=yes driver=ath9k driverversion=3.2.0-27-generic-pae firmware=N/A ip=192.168.1.82 latency=0 link=yes multicast=yes wireless=IEEE 802.11bgn
       resources: irq:17 memory:fbff0000-fbffffff
  *-network
       description: Ethernet interface
       product: AR8132 Fast Ethernet
       vendor: Atheros Communications Inc.
       physical id: 0
       bus info: pci@0000:01:00.0
       logical name: eth0
       version: c0
       serial: bc:ae:c5:27:61:81
       capacity: 100Mbit/s
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress vpd cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=atl1c driverversion=1.0.1.0-NAPI firmware=N/A latency=0 link=no multicast=yes port=twisted pair
       resources: irq:46 memory:f7fc0000-f7ffffff ioport:ec00(size=128)

thanks.