DO YOU USE A OPTICAL MOUSE? beucase they can sometimes "warp" around the screen if used on the wrong surface. if it is a ball mouse it may require cleaning inside.
My mouse used to do that all the time, its optical. After i bought a "crystal mouse mat" specially designed for optical mice it never did it again, mouse mat cost £5 thats about $7
youre probaly using it on the wrong surface, either buy a special mous mat like dragon2309 said, or try using a few bits of paper, it worked with my friend