I get an cron reset request when I activate post expirator:
Reset Cron Event: Status: RESET NEEDED
Resets the cron event and removes any old or stray entries.
Reset Cron Schedule: Status: ERROR WITH FILTER
Displays the cron minute schedule status for post expirator.
Post Expirator Debug Logging: Status: Enabled
This is my schedule:
Date Event Schedule Interval (seconds)
Thu, 09 Aug 2012 11:43:11 +0000 tweet_import_scheduled_hook everyquarter 900
Fri, 10 Aug 2012 09:09:33 +0000 wp_scheduled_delete daily 86400
Could it have something to do with an other cron?