Erratic Mouse behaviour

[Zembu]

I've seen posts here before on this topic, but now can't find them. My mouse pointer does strange erratic movements. The problem is not always there, but seems to be getting more frequent. Usually it starts this way - I move the mouse on the screen and it forms a rectangle as if to select. Escape key stops it, but it returns.
In Outlook or in a document, I can be typing and then it moves so what you type ends up somewhere else. That has happened several times while I type this.
In Windows Explorer supposing I'm moving the pointer to select something, before I get there it may highlight another file and as I am moving the mouse it will be dragged somewhere else.
I tried using the process monitor to see if some software comes into play at the time it happens but so far haven't seen anything obvious.
It's not the mouse itself as the same happens with a different mouse. I've tried uninstalling the drivers and they reinstall of course and makes no difference. Also tried searching for better drivers didn't find any. Can't find any indication on line that this a virus behaviour. Am using Malwarebytes anti-virus and it hasn't found anything. Also used Malwarebytes rootkit checker and found nothing.
I've noticed many posts about such problems on Google.

[PHP Secure]

Hello, actually, I also encounter this problem sometimes, unfortunately, I haven't figured out a solution for it yet.