Fixed by not using kaffeine any more with konqueror. Please reopen this bug if you think it has been closed in error.
Thank you for reporting this bug. ** Changed in: kdebase (Ubuntu) Status: Unconfirmed => Fix Released -- race condition in konqueror, backtrace shows XUnlockDisplay in libx11 as possible cause https://launchpad.net/bugs/20271 -- kubuntu-bugs mailing list kubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/kubuntu-bugs