It sounds like something is wrong with your system which is somehow triggered by alarm-clock. Anything suspicious in the kernel or system logs? /var/log/kern.log or /var/log/syslog or /var/log/messages or /var/log/Xorg.0.log may contain some useful info.
** Project changed: alarm-clock => alarm-clock-applet (Ubuntu) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1450692 Title: since upgrade to Xubuntu 15 computer freezes when alarm sounds To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/alarm-clock-applet/+bug/1450692/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
