Mouse cursor moving on its own
My mouse cursor keeps moving by itself; it darts quickly across the page, usually on a diagonal. Has this happened to anyone before? I don't download much, expect for torrents for my music...and I stream videos. Other than that I just check email, facebook, etc. I don't have shared internet connections or anything. Could it be the mouse, a hardware problem versus a software problem or virus??
Thanks for the help!
iMac, Mac OS X (10.5.8)