Voici la solution (temporaire car toujours pas de fix chez ATI) :
Pour ceux qui n'arrivent plus à upgrader les drivers (bug BSOD concernant uniquement les CF de 4850 sous vista x64) :
(1) Make sure that your 48xx Crossfire system is running normally with a set of CATs that works for you. For me, that was 8.10.
(2) Install the CAT 8.11's normally--I use the full CCP and driver install package.
(3) After install, reboot the system immediately into SAFE MODE.
(4) From SAFE MODE, go to ADMINISTRATIVE TOOLS/SERVICES and locate the ATI External Event Service. Set this service to DISABLED. Reboot normally into your standard operational mode.
(5) After boot, from the systray open the CCP. Go to the Crossfire section. You should see Crossfire check box empty even though you've installed the drivers with your Crossfire bridges connected. Check the box and hit "Apply" and be amazed to see that your system does not immediately bsod! Hit "OK" to close the CCP.
(6) Reboot into your normal operational mode again, go to CCP from the systray and check out your Crossfire settings which should now register checked, indicating that your Crossfire system is operating normally. You are done and problem solved. Since the ATi External event service is now disabled, however, you will have to reboot between turning crossfire on and off, but your bsod's should now be a thing of the past.
There's a method to this madness. You have to install the 8.11's prior to going into safe mode to disable the AEE service, and that's because when the drivers install they automatically set this service to "automatic," so if you try disabling the service before you install the 8.11's it won't help since the driver install will reset the service to automatic.