I posted this message in another section, but I think it is related.

http://chaldee1.gotadsl.co.uk/~richardb/upload/showthread.php?p=10001#post10001

We recently purchased a MacPro, I think 2006, with ATI 1900, Catalyst 4.40 m329 and we are having the same problem when trying to work with 3 mixer Keystone.
The Snow Leopard 10.6.6 operating system has been installed at 0.

Any suggestions?

E Cueto