"I know what you mean rojash about pressing the mouse wheel but in my case it is the contents of the web page scrolling up and down at a frantic speed, more so if I try to get back to the top of the page. "
Well, that's exactly what the behaviour I would expect if you've accidentally clicked the mouse wheel.
"The title and task bars do not roll."
So the problem is not with monitor at all, it's definitely connect with the mouse.
"sometimes when I use the mouse scroll wheel, this changes the size of the screen instead of moving the web page up or down? "
That normally happens if you hold down the CTRL key and use the scroll wheel.