I have a Logitech G500 mouse. I've had it for 6 months with no problems. I am having trouble now though. When I scroll the mouse wheel sometimes I will stop and the scroll bar will jump an inch or so. It does it in Firefox, Win IE 7 and in Windows explorer. My OS is XP Pro. I reformatted and reinstalled XP (not for this reason) and I figured it would go away but it didn't. Any ideas?