PASCALFORGET Yep... The driver have always been the issue with the PowerMate. Taught of reinstalling it to scroll down faster, and with 10.5.6 the pointer moves right (or left) when I scroll up or down. After a few rotations, the pointer moves out of the window (in my case, a Firefox page), and the scroll changes to volume up or down...
I'll hope for an update. Meanwhile, I'll keep using the scroll wheel on my mouse.
(Version 2.1)