For one thing, the scroll wheel doesn't respond at all. Also it's impossible to use the mouse normally as anything clicked on just disappears up into the side panel. I can drag the item to the screen and it will usually only stay there as long as I hold down the left click. The rest is really impossible to describe properly, other than to say that stuff jumps about and / or disappears unpredictably, and when there is a screen display it shimmers every time the mouse is moved. Also the side display of which window is active will often oscillate rapidly between its two states. I can't even use the file manager to look at any files because of this condition.
Another thing is that if I click on, say, settings then it's impossible to select what i want to run because the display scrolls up and down unmanageably when I use the scroll bar to try and select.
I have checked that the mouse itself is in fact OK and working correctly.

I am having to use this forum via a windows machine (and the same mouse!)!