I just received my imac 24" 2.8 ghz 2gb mac...Issue is while using the wired mouse(yes it's from apple and wired into the keyboard) The curser will be working fine. Then all of a sudden it disappears off the screen. I have to move the mouse around till it appears again. This can happen every few seconds, mins or take longer. I've used mouse pads and not. Nothing seems to help. Any suggestions?