Kernel update breaks wlan

Binary package hint: linux-restricted-modules-2.6-386

Since the security update to kernel 2.6.17-10-386 (linux-image-2.6.17-10-386 2.6.17.1-10.34) if have problems with my wlan. The wireless network device isn't present anymore.

I use a Atheros AR5212 in a IBM Thinkpad T43.

Since the kernel update sudo ifup ath0 reports the following:
Error for wireless request "Set Encode" (8B2A) :
    SET failed on device ath0 ; No such device.
Error for wireless request "Set ESSID" (8B1A) :
    SET failed on device ath0 ; No such device.
SIOCSIFADDR: No such device
ath0: ERROR while getting interface flags: No such device
SIOCSIFNETMASK: No such device
ath0: ERROR while getting interface flags: No such device
Failed to bring up ath0.

But lshw still says:
  *-network UNCLAIMED
       description: Ethernet controller
       product: AR5212 802.11abg NIC
       vendor: Atheros Communications, Inc.
       physical id: 2
       bus info: pci@04:02.0
       version: 01
       width: 32 bits
       clock: 33MHz
       capabilities: bus_master cap_list
       resources: iomemory:a8400000-a840ffff irq:11

And lspci says:
04:02.0 Ethernet controller: Atheros Communications, Inc. AR5212 802.11abg NIC (rev 01)

If I use the old kernel 2.6.15-27-386 everything is fine again.

I noticed that with the new kernel an older version of the madwifi driver [wlan: 0.8.4.2 (0.9.2)] is used. In the 2.6.15 kernel wlan: 0.8.6.0 (EXPERIMENTAL) is used.

The result is, that dmesg reports the following on boot:
[17179591.536000] ath_rate_sample: Unknown symbol ath_hal_computetxtime
[17179591.548000] ath_pci: Unknown symbol ath_rate_tx_complete
[17179591.548000] ath_pci: Unknown symbol _ath_hal_attach
[17179591.548000] ath_pci: Unknown symbol ath_rate_attach
[17179591.548000] ath_pci: Unknown symbol ath_rate_newassoc
[17179591.548000] ath_pci: Unknown symbol ath_hal_computetxtime
[17179591.548000] ath_pci: Unknown symbol ath_rate_dynamic_proc_register
[17179591.548000] ath_pci: Unknown symbol ath_hal_mhz2ieee
[17179591.548000] ath_pci: Unknown symbol ath_hal_detach
[17179591.548000] ath_pci: Unknown symbol ath_hal_probe
[17179591.548000] ath_pci: Unknown symbol ath_rate_node_cleanup
[17179591.548000] ath_pci: Unknown symbol ath_rate_detach
[17179591.548000] ath_pci: Unknown symbol ath_rate_node_init
[17179591.548000] ath_pci: Unknown symbol ath_rate_findrate
[17179591.548000] ath_pci: Unknown symbol ath_hal_init_channels
[17179591.548000] ath_pci: Unknown symbol ath_rate_newstate
[17179591.548000] ath_pci: Unknown symbol ath_rate_setupxtxdesc
[17179591.548000] ath_pci: Unknown symbol ath_hal_getwirelessmodes

What happened on the update?