This seems to happen on a current Windows 10 Insider build (Build 19013) with the Synaptic touchpad drivers from the HP website.
The issues I was having was that when I used the buttons on the touchpad, Search appeared. This could be temporarily resolved by killing 'Synaptics 64-bit touchpad enhancements' in Task Manager. However, it kept restarting itself.
This can be solved by disabling the service that starts this programme:
- Go to the Start menu, search for and open "Services".
- Find SynTPEnhService.
- Right-click on the service and select "Properties".
- Set "Startup type" to "Disabled".
- Restart, or kill Synaptics 64-bit touchpad enhancements in Task Manager again.
Windows 10 takes care of precision scrolling and gestures, so there is little need to run enhancement software that comes with the drivers.