Mix Console faders unusable

I had, like most people, had a problem with Mix Console behaving erratically under Cubase Artist 7.03 but since updating to 7.04 find that the cursor / pointer jumps to changing width (horizontal) for no apparent reason and refuses to allow me to change channel faders (vertical). Closing the Mix Console and re-opening it makes no difference (it did with the channel strip labels disappearing - a previous problem). I had thought about updating video card drivers to see if it had any effect but the drivers for the card in my iMac (ATI Radeon HD 5750 1024 MB) seem impossible to find.

Does anybody else have this problem and is anybody able to help me solve it?

Thanks in anticipation,