Wifi Networking shuts down frequently

Mint Release 12 Lisa
Kernel 3.0.0-12-generic
Gnome 3.2.1

This was a problem in the past, then disappeared for a while, and is now back.

At least once daily I'll return to my PC, enter my password to log back in, and be presented with a dialog asking me to enter my networking password. I'll enter it, but the WIFI will never re-connect. Only a reboot brings it back

This problem has become significant in the last week or two, so I assume there's been some kind of update that triggered it.

I'm using a Dell AMD dual core 64 system

       *-network
             description: Wireless interface
             product: AR5008 Wireless Network Adapter
             vendor: Atheros Communications Inc.
             physical id: 9
             bus info: pci@0000:01:09.0
             logical name: wlan0
             version: 01
             serial: 00:21:91:01:10:d4
             width: 32 bits
             clock: 66MHz
             capabilities: bus_master cap_list ethernet physical wireless
             configuration: broadcast=yes driver=ath9k driverversion=3.0.0-12-generic firmware=N/A ip=192.168.0.197 latency=168 link=yes multicast=yes wireless=IEEE 802.11bgn