Comment 7 for bug 791007

Thank you for your backtrace, unfortuately it is not very usefull when the application did not crash.
So I guess we'll have to wait for another crash.

To help you get the backtrace properly you could enable apport. For more information see https://wiki.kubuntu.org/Apport#How to enable apport
As your crash it not reproducable, it might be convient to keep apport enabled until the crash occurred again (instead of enabling it once), so editing /etc/default/apport seems your best option at the moment.