[Suicide Junkie]

Well, the second is due to having a low framerate. Hardware limited... mitigated by patience and compensating by slowing down before you get to where you want to click.

The former shouldn't really happen.
Unless you're moving the mouse around while a screen is loading or something, and the processor is busy.
An outside possibility is one of the accessibility features of windows, where it will make your cursor jump to the buttons of a message box when one pops up. You could try disabling that.