Jumping cursor highlights, deleted, overwrites words. Windows 10 and Windows vista.

The cursor on my Dell inspiring 1545 jumps randomly, sometimes highlighting and

deleting or overwriting words. It did it in Windows Vista but I am now surprised on upgrading to Windows 10 and a new hard drive it is worse.

I have:

1. Removed drivers for mouse pad

2. Installed touch freeze

3. Done virus scans including boot sector scans from both Avast and AVG rescue disks.

4. Experimented with various options in the mouse properties in control panel as instructed by threads on various forums.

All to no avail.

It is worst in word and notepad but sometimes happens in yahoo mail.

I've never spilled anything on this laptop.

Someone suggested a build up of static electricity over time as the cause but it happens as soon as I turn it on.

Any suggestions gratefully received. This is driving me scatty. I've just spent €120 upgrading my machine and now just want to throw it in a skip.