Jan 23, 2013 11:42 AM in response to henryfromgreen cove springs Had the same problem. Here's the process I went through to getting it working again: Tried fresh batteries. Clicks worked, but no mouse tracking. Another set of fresh batteries. The same result. Tried removing and re-adding the mouse in the Bluetooth Preferences. No difference. Found a blog post that suggested cleaning the battery contacts. Mine looked nice and shiny, but I scrubbed them anyway. Still no good. Went into Bluetooth preferences, highlighted the mouse then under the gear menu, clicked "Update Services" then "Monitor Connection RSSI". Monitor Connection RSSI opened a new window with a graph. It took a few seconds for it to start plotting data, but as soon as it did, the mouse began working correctly. OR Feb 1, 2013 12:14 AM in response to henryfromgreen cove springs Delete the extension named USBOverdrive.kext in the extensions folder under \System\Library\Extensions. Restart the computer and it work.