I had the same problem with ubuntu 11.10 running Gnome Classic... This is what I did as a test to see if it might fix it:
started: Symnaptic Package Manager Remove mousetweaks reinstall xserver-xorg-input-mouse did not install mousetweaks again. time will tell if that has an effect on it. Don -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg-server in Ubuntu. https://bugs.launchpad.net/bugs/41301 Title: Mouse clicks stop working sporadically To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/41301/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : [email protected] Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp

