After reboot, ndiswrapper stops working

I have a toshiba A215-S4747 laptop, with a Atheros 5006 wifi card. I am using ubuntu 7.10 RC x64.
I have installed wifi with ndiswrapper since Mad-wifi drivers did not work.
After installing ndiswrapper and the winxp64 driver, I reboot the system and everything works perfect. I can connect to secure and non secure wireless networks, get IP by DHCP and so on. But once a reboot the system, I cannot connect to any wifi network (wired networks have no problem at all).
I can scan the air, and I can see all networks available, but it is impossible to connect to any of them (insecure, wep, wap, wap2, etc).
I know how to make it work again:
uninstall windows driver, uninstall ndiswrapper.
Reboot.
Install back ndiswrapper and winxp driver.
Set ndiswrapper to load on startup.
Reboot.
After all this, the wifi card works again perfectly. But if I reboot, I get the same error, although I keep all my network configuration, it just don't work. Ath_PCI module is blacklisted.

More information:
When everything works fine, ifconfig command shows:

wlan0 Link encap:Ethernet HWaddr 00:1B:9E:37:65:7B
          inet addr:192.168.0.101 Bcast:192.168.0.255 Mask:255.255.255.0
          inet6 addr: fe80::21b:9eff:fe37:657b/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:43240 errors:0 dropped:0 overruns:0 frame:0
          TX packets:29805 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:52729980 (50.2 MB) TX bytes:4260225 (4.0 MB)
          Interrupt:19 Memory:f8200000-f8210000

and dmesg | grep ndiswrapper returns

[ 33.029799] ndiswrapper version 1.48 loaded (smp=yes, preempt=no)
[ 33.415459] ndiswrapper (link_pe_images:576): fixing KI_USER_SHARED_DATA address in the driver
[ 33.417283] ndiswrapper: driver net5211 (,07/26/2007,5.3.0.67) loaded
[ 33.417607] ndiswrapper (ZwClose:2244): closing handle 0x0 not implemented
[ 33.830516] ndiswrapper: using IRQ 19
[ 34.046383] usbcore: registered new interface driver ndiswrapper

and ndiswrapper -l

net5211 : driver installed
        device (168C:001C) present (alternate driver: ath_pci)

When things go wrong, dmesg | grep ndiswrapper returns:

[ 34.110560] ndiswrapper version 1.48 loaded (smp=yes, preempt=no)
[ 34.314518] ndiswrapper (link_pe_images:576): fixing KI_USER_SHARED_DATA address in the driver
[ 34.316298] ndiswrapper: driver net5211 (,07/26/2007,5.3.0.67) loaded
[ 34.316605] ndiswrapper (ZwClose:2244): closing handle 0x0 not implemented
[ 34.729367] ndiswrapper: using IRQ 19
[ 34.938008] usbcore: registered new interface driver ndiswrapper

and ifconfig

wlan0 Link encap:Ethernet HWaddr 00:00:00:00:00:00
          UP BROADCAST MULTICAST MTU:1500 Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
          Interrupt:19 Memory:f8200000-f8210000

Strangelly, MAC address has only zeros (I don't know if it is important or not)
Finally, iwconfig shows

lo no wireless extensions.

eth0 no wireless extensions.

wlan0 IEEE 802.11g ESSID:off/any Nickname:"gonzalo"
          Mode:Managed Frequency:2.462 GHz Access Point: Not-Associated
          Bit Rate:54 Mb/s
          Power Management:off
          Link Quality:0 Signal level:0 Noise level:0
          Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
          Tx excessive retries:0 Invalid misc:0 Missed beacon:0

I hope this report helps you. Best regards.