Elitebook 840 Synaptics Touchpad Not Working Properly

[dj2hoff]

2019 HP Elitebook 840 G5 with Windows 10 (64-bit). No recent OS updates or installations.

I've suddenly started having issues with my touchpad. With the latest drivers I could find  (19.5.9.49), no matter how I move my finger on the touchpad, the cursor goes to one of the corners of the screen. Depending on where I placed my finger, the mouse would skip to a different corner of the screen.  The pointing stick nub works as normal and the clickpad buttons worked as normal.

By rolling the driver back to an earlier version (19.5.9.41), I was able to make the touchpad behave somewhat normal, but the sensitivity was greatly decreased and multi-finger gestures no longer work. The Synaptics Touchpad Settings Manager also only has options for touch sensitivity and button settings, so I don't know how to get the gestures back.

The old drivers are usable, but ideally I would like to get gestures back at least. I also don't know why the new drivers suddenly stopped working.

Thanks in advance for any assistance

[lakerol · Accepted solution]

Install "Intel Serial IO Driver" 

That should fix your touchpad. 

https://support.hp.com/us-en/drivers/selfservice/swdetails/hp-elitebook-850-g6-notebook-pc/26609805/... 

[dj2hoff]

That did it, thanks!