[ubuntu] Ubuntu 16.04 LTS on Dell E5420 Mouse Pointer Problem

I am using Ubuntu 16.04 with all the updates on a Dell Latitude E5420.
I use the touchpad and the mouse pointer has a brain of its own.
It jumps to another location in a doc and the characters typed are inserted in that position.
Sometimes, selections are made so the new typed char will overwrite the selection and I need to use the undo command in the browser or libre office or yahoo email or google docs.
i tried this fix but it did not work. I lost the pointer altogether and so had to revert the update to the grub init file.

https://www.youtube.com/watch?v=4-cGqVLXyrA

Please help with a solution. I did search but found nothing of recent date for the same machine/issue.

Thanks in advance.