Logitech LX7 is malfunctioning after battery change.

My mouse is haunted! The dying battery light on my Logitech LX7 cordless optical mouse started pulsing so I replaced the batteries (after a few days, I'm not made of batteries). After doing so things got weird. The scroll wheel stopped working and web pages began scrolling down by themselves (but never up) or when I simply moved the pointer on the page. Nothing other than the batteries have changed. I pressed the reset button, I have powered down the mouse, I have unplugged the usb do-hicky from the back of the computer, I have rebooted the computer, I have downloaded the newest software from the Logitech website. Any ideas? Yes the batteries are in correctly.