Server :: When Cron Is Running, Monit Loses Its Connection To Postfix?

I've run into a strange problem on one of the servers I maintain. It's running CentOS 5, fully up to date. The server has Monit installed via RPMforge, and runs Postfix as its MTA. Every day at about 4:20am, when cron is running, Monit loses its connection to Postfix. As far as I can tell, nothing is actually going wrong with Postfix and it's always restarted just fine. I run a couple of Debian servers with very similar setups, and the problem does not occur on them.

Perhaps related, other daemons on the CentOS box often lose their pid files at the time when cron runs, which results in Monit thinking they're not running. One service in particular (zarafa-dagent) is so bad for this that I've had to completely disable monitoring of it in Monit. Again, this problem doesn't occur on the Debian boxes I maintain.The problem isn't hugely urgent as everything still runs fine, but it does mean that pretty much every day I get false positive mail alerts from Monit, which is (a) annoying and (b) makes me more likely to miss a real alert.