This problem bothers me a little. The authentication server failed during a cron job that referenced a specific account. Ubuntu could not authenticate the account, and id username failed. So the account was written to the /var/spool/cron/crontabs/ and any time I tried to edit the cron file under /etc/cron.c/username-cron-file, the reload would fail:
cron[17959]: (*system*username-cron-file) RELOAD (/etc/cron.d/username-cron-file)
cron[17959]: Error: bad username; while reading /etc/cron.d/username-cron-file
cron[17959]: (*system*username-cron-file) ERROR (Syntax error, this crontab file will be ignored)
cron[17959]: (username~) ORPHAN (no passwd entry)
I deleted the spool entry and was able to recreate the cron file.
