This is a new issue as of a week or so ago. Running 12.04 64bit (Kernel 3.2.0-29-generic; Gnome 3.4.2) Unity system with a Logitech wireless Laser mouse and EX110 wireless KB. Upon initial boot,neither left nor right mouse buttons work for selecting anything other than items in top system tray (e.g., gwibber, sound, system settings) and the Dash. The pointer will move normally, but clicking on a file on my desktop does nothing (icon will not show as being highlighted). The temporary (I hope) fix for me has been to simply log off and back on.... I do not need to warm boot (though that does resolve the matter too), just logout & on. Nb: the keyboard functions w/o issue. I have tried a wired mouse (usb) and found the same results. This is not debilitating, but certainly annoying and makes my "try Ubuntu, it's great" pitch that much harder.