Perhaps someone can help me.

Very often it appears the mouse cursor moves irregularly: it occasionally stops moving; when pressing the middle mouse button a current page, document, etc., will sometimes scroll slightly up or down; sometimes the cursor stops and suddenly appears somewhere it shouldn't be; sometimes the cursor is suddenly selecting a menu; sometimes a popup menu appears even if I haven't right-clicked; etc., etc.

Sometimes there are various combinations of those points up there in different degrees.

Everything -- as far as I know -- is installed properly and I am not one who would mess up a system. It leads to somewhat terrifying thoughts regarding the perceived possibilities.

He who has the solution will be endowed with... well, I don't know -- a cookie? A beer?