Hi guys I'm posting this in the iMac forum and not the peripherals forum as the problem occurs with all mice so isn't related to the mouse hardware specifically. I've just setup a second hand iMac Core 2 Duo running Lion (all up-to-date). I've gone into mouse preferences and set the right button to be the secondary function (i.e. right-click) but both buttons still do the primary click function. I've tried a Mighty Mouse (wired), and Mighty Mouse (Bluetooth), as well as a Dell mouse. All work fine on other Macs but won't right-click on the iMac. I've rebooted the machine multiple times, I've un-paired the bluetooth mouse and re-paired, plugged and unplugged the wired mice while rebooting in between. I've tried setting the left button to be the secondary button. Again, both buttons remain the primary. Here's my mouse settings. Any help would be much appreciated! Cheers.