After more queries in Launchpad it seems that this problem can be related to ATI KMS.
I have disabled it for now and will see how it will affect the situation. -- Freezing of tasks failed after 20.00 seconds (1 tasks refused to freeze) https://bugs.launchpad.net/bugs/533788 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
