Failed to stop TX DMA in 100 msec after killing last frame, ath: Failed to stop TX DMA! cause my scans not to work right.

I almost had a breakthrough (but it is not repeatable).
I did:
modprobe ath9k debug=0xffffffff

and it WORKED. :-)

It didn't work when I rebooted.

I would suspect a hardware problem except it works 100% in kernel 2.6.4.