content: I tried this device on 3 computers. xp, 2000, and 98 SE. Track ball would only give horizontal motion. IOGear support had me try deselecting scroll wheel on the mouse driver. No good. Maybe I received the 1 in 1000 bad ones....but a lot of wasted time. As with everything else with this outfit, AMAZONs return process top notch painless and quick.