The Synaptics driver is what most laptops use to allow the user to control the laptop cursor via the built-in touchpad. In addition to disabling the touchpad this way, Lenovo also recommends you disable the Synaptics driver for the touchpad device.

Please note: According to Lenovo, the touchpads on their laptops have been set to enable automatically whenever you first turn on the computer or wake it from hibernation, so you may need to repeat the steps above if you notice the issue recurring after first disabling the touchpad.