Kensington Turbo Mouse software will take precedence at startup over the settings contained in the Apple Mouse control panel. The mouse uses the values allocated in the Turbo Mouse CDEV (v3.0), or the Turbo Mouse Control application program (v4.0), and respond accordingly. As with the Mouse control panel, setting the Turbo Mouse controls to the fastest setting can be inoperable for some users-they just can't click fast enough. The range of values selected for the double click speed in the Turbo Mouse Control Panel was chosen to accommodate the 5th to 95th percentile users. This means that if you select the farthest extreme to the right some users might have a problem generating a double click. Try decreasing the speed in the control panel.