Version: 3.5.3 (using KDE 3.5.3, Kubuntu Package 4:3.5.3-0ubuntu0.1 dapper) Compiler: Target: i486-linux-gnu OS: Linux (i686) release 2.6.15-23-k7 If you check the box for "Silent" when creating or modifying a job, you'll be unable to save the changes. Executing from console shows a message saying that the file has wrong format (bad minute). I guess kcron is generating an invalid crontab file when this option is checked. The task I was using for testing was a daily one, with all minutes checked (maximum frequency allowed by kcron).
Confirming with KCron 3.5.3 (Debian Sid package). I get the following output on the console: "/tmp/kde-stefan/kcronOvkJMa.tmp":9: bad minute errors in crontab file, can't install.
Oops, this is a dupe actually. *** This bug has been marked as a duplicate of 85425 ***