If any one is interested in re-assigning their 'extra' mouse button in Autocad, This may be on interest.
I recently upgraded my Logitech mouse, and I like the idea of having the escape function assigned to a mouse button, rather than using the ESC key all the time.
The mouse I have has a screen forward/back buttons that has no function in Autocad, so after much searching I found a utility on the Logitech site called UberOptions, that shows an enhanced Logitech Setpoint program for your mouse.
When you run it it enables you to set any function to any button which I could not do in Logitech Setpoint.
Problem solved.
Al.