[Zope] Zope/Xron/Apache

Hello, I am having problems with xron and virtual hosting. The zope/apache virtual host set up works fine, but when I have a xron job that doesn't run properly, it hangs the whole system. Furthermore, when I stop and restart zope, the restarted process also hangs (it never gets to the line about Z HTTP server). Any hints from anyone would be greatly appreciated. Thank you, Shilpa