User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:16.0) Gecko/20100101 Firefox/16.0 Build ID: 20121025210744 Steps to reproduce: I tried to import calendar data stored in an .ics-file, which I had exported before from KOrganizer (KDE calendar program). Actual results: I get the following warning ********************************************** Unresponsive script A script on this page may be busy, or it may have stopped responding. You can stop the script now, or you can continue to see if the script will complete. Script: file:///usr/lib/mozilla/extensions/%7B3550f703-e582-4d05-9a08-453d09bdfdc6%7D/%7Be2fda1a4-762b-4020-b5ad-a41df1933103%7D/components/calStorageCalendar.js:2017 *********************************** When I click "Continue" it asks me, which calendar I want to import into, but the dialog is not responsive. Then, after a long time, a new warning pops up: ********************************* An error occurred when writing to the calendar JoachimsKalender! Error code: MODIFICATION FAILED ********************************** and the unresponsive script warning comes back, but can be clicked away.

I can't reproduce this, but its probably related to cpu vs file size. Confirming because I do see the throbber running. The solution would be to make the importer asynchronous, and possibly bug 302390.