This seems fixed on 4.1 RC1 packages. I just updated yesterday, and then it stoped crashing. I'll attach the aptitude log.
** Attachment added: "aptitude.txt" http://launchpadlibrarian.net/16147250/aptitude.txt -- System freezes when reenabling compositing in kwin-kde4 https://bugs.launchpad.net/bugs/249251 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs