I got a Logitech wireless optical mouse (Cordless Click! Plus to be exact) as a gift three weeks ago. I took some regular alkaline AA batteries and installed them. Used the mouse for two weeks and no problem Just the other day I got some lithium batteries on a great deal. Because of their lighter weight I put two in the cordless mouse thinking they'll also last an extremely long time. However the system just notified me the batteries were at critical level and need to be replaced! I've used lithium batteries before in cameras and GPSr units and love their weight advantage, long life and negligable power loss in cold temps. However I'm completely baffled by a mouse draining lithium batteries in two days. Can any cordless mouse users offer some advice?