I can confirm this same issue. I'm also running F10 with the latest KDE 4.2 from the testing repo. I've cleared /tmp and /var/tmp as well. No backtrace either. Blank screen saver, desktop effects enabled too. The only thing that appears consistent is that kwin only crashes after the screen has been locked for an extended period of time (i.e. overnight). Brief intervals (minutes to couple...
2009-02-03 21:30:54 UTC in KDE Packaging Project