ATI Mobility FireGL V5250 - Very strange

Hi,

I have a IBM Thinkpad T60p with ATI mobility FireGL V5250 graphics adapter.
The driver Lenovo provides for this is useless and make the computer not
bootable.

I have found drivers from Microsoft Update WDDM signed drivers. The strange
thing is that the driver for V5250 doesn't work, and stops the computer from
booting, just cant get it working.
Then I installed the Microsoft WDDM signed driver for ATI mobility V5000,
and now it's working? Can someone explain this :-)
I'm just afraid that the V5000 driver don't use all the features of the
V5250 adapter.

Someone have a solution to this?