I'm working with this software with Leopard. No problem on older dual G5 and MacBook with Intel.
I did have a few problems that Stefan helped me with.
I might suggest you go into your Library/Application Support/eMotionDng folder and move (and probably later discard) the 'dat' and 'ref' files. these will be auto-replaced if you then re-install the Sinar software. This files are specific for your back (or, you can copy these two files from the computer that is working). These are the defaults you get when you click on 'default' white ref button.
alternately, do you have more than one tab on the white ref pop out window? if you do, you may be using a set of data for another back. by clearing out the above folder, this issue will also be fixed.