Wireless mouse

So I bought the Microsoft wireless Natural Multimedia Keyboard and wireless Intellimouse Explorer 2.0 mouse. I like the keyboard, but the mouse is pissing me off. I keep getting the “batteries are low in the mouse, change them now or the mouse is likely to burst into flames” alert window popping up. Arg. I changed the batteries three times. It’s possible the batteries really are low – I’m not sure how long I’ve had them. They were in my freezer. Also the mouse just seems sluggish to me. Remember before optical mice, and you’d get a little crud on the ball and the mouse would get sorta stuck for a microsecond and sort of track jumpily? That’s what it’s like. It really bugs. Maybe there’s something interfering with it or maybe the batteries really are low. Dunno. I moved the basestation gizmo away from the cordless phone which doesn’t seem to have helped much. Anyone have any suggestions?