This happens to me every few days too. I'm on Ubuntu Lucid 64bit with a Geforce 8400 GS with recommended proprietary drivers running two monitors. My keyboard inputs do not respond when this freeze happens. I tried the 'RightOf' change as suggested in a few comments but upon continuation of crashes I restored the old config.
** Attachment added: "xorg.conf" https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/570151/+attachment/2287724/+files/xorg.conf -- 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/570151 Title: mouse stuck between screens with xinerama To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/570151/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp