Our IntelliMouse Explorer 3.0 USB has recently changed its behavior. Even the lightest touch will result in a response that would be expected by 4 or 5 clicks of the mouse. It is most difficult now to just hightlight something....it just wants to OPEN, rather than hightlight. I may have to stop and retry hightlighting 5 times to get it right. Are optical mice just prone to problems of this kind?