ATI Video Crossfire Device Error (Code 12)

Hi Have had ATI Crossfire running on two x1950x cards without problem on XP.
Updated to Home Premium and almost installed Vista compatible drivers on the
two graphics cards. The Crossfire Edition card appeared to work but the
standard X1950X failed to install as the device had a "This device cannot
find enough free resources that it can use. (Code 12)" error. Some of the
websites state that you should look for conflicts - but the card under
Resources in Properties says no resources allocated due to lack of
resources. Other webistes suggest changing the UMA Buffer size - that doesnt
appear in the AMI Bios I have on my ASUS motherboard. Can anyone help please?

Thanks