Linux: weird intermittent Atheros Wifi solved

Download http://linuxwireless.org/download/compat-wireless-2.6/compat-wireless.tar.bz2
Unpack and compile as root:

./scripts/driver-select atheros
make -j3
make install

make unload
make wlunload
make btunload

rmmod ath9k
modprobe ath9k