Couldn't help noticing that you have an Intel Mac but are running 10.4.11

Nothing wrong with that but I wondered if the software that came with the mouse was suitable for either of those things.

The Kensington website only shows 4 drivers, 2 for slimblade and 2 for mouseworks and only one of them was anything close to being up to date.

Did you ever contact Kensington, they have free tech support, about the problem.

P