Comment 9 for bug 269253

I am having this same issue on Hardy after the recent kernel upgrade:
Linux laptop 2.6.24-21-generic #1 SMP Mon Aug 25 17:32:09 UTC 2008 i686 GNU/Linux

$ dmesg | grep ath
[ 29.254904] ath5k_pci 0000:03:00.0: registered as 'phy0'
[ 29.691437] Registered led device: ath5k-phy0::rx
[ 29.691455] Registered led device: ath5k-phy0::tx
[ 29.691458] ath5k phy0: Atheros AR5424 chip found (MAC: 0xa3, PHY: 0x61)
[ 29.709765] ath_hal: module license 'Proprietary' taints kernel.
[ 29.713619] ath_hal: 0.9.18.0 (AR5210, AR5211, AR5212, RF5111, RF5112, RF2413, RF5413)
[ 30.113393] ath_pci: 0.9.4
[ 59.221867] ath5k phy0: noise floor calibration timeout (2417MHz)
[ 59.221878] ath5k phy0: can't reset hardware (-11)

It was working fine with the 2.6.24-19 kernel.