If it's randomly double clicking then it could be Windows/the mouse driver malfunctioning; the mouse cable; a virus or something going crazy with the mouse itself. You should try another mouse to see if the same thing happens. I suspect you're dealing with a faulty mouse.

If it's jumping about the screen then you should have a look at the surface you're using it on. If it's an optical mouse and it's a shiny/uneven surface then it can jump about. Also, check to make sure that little hairs haven't gotten stuck in the optical bit underneath.