Install latest Synaptics drivers ( I recall I did this anyway) FIRST download and update the Serial I/O driver. get latest updates from Acer support here and put in your serial number and (can used an external mouse temporarily if necessary)
If I recall correctly this is what I did to solve touchpad problems temporarily, My touchpad was also jittery and erratic before and after installation and before windows updates and after windows updates. I had touchpad problems (touchpad setting not visible and touchpad not working properly). please help me I have the new Acer Nitro 5 AN5-15-55. You could try reinstalling the Serial IO driver, right click 'I2C HID Device'(with yellow triangle) in Device Manager under Human Interface Devices, click Update driver, reboot and see whether the yellow triangle disappears.
