What have you tried so far?
I tried manually deleting the one PS2/Mouse driver that pertains to the touchpad, and reinstalling it, which didn't work for me. Also I've seen folks with a wireless mouse, that have issues with that, which I didn't. Also mouse sensitivity can be an issue, setting the sensitivity lower in control panel/mouse/pointer options.
I've also seen a third party software, "touchfreeze" mentioned, to fix the problem but I don't know anything about that.