There are a number of reasons why you might want to disable your laptop’s touchpad when another mouse is plugged in. You could be touching the mousepad when you type or the touchpad could be causing problems with the mouse that’s plugged in. Wouldn’t it be nice to have the laptop automatically disable the touchpad when a USB mouse is plugged in? The good news is that you can!
To disable the touchpad when a USB mouse is plugged in, right click the Synaptics icon in the task bar and go to the properties (alternatively go to the Control Panel and click on Mouse). On the Device Settings tab tick the box to Disable touchpad when USB mouse is present.
If you don’t have a tickbox to disable the touchpad when a mouse is present, you can also do this in the registry. click Start and type Regedit then hit enter. Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Synaptics\SynTP\Configurable and change the data value of DisableTouchPadIfMousePresent to 1.