SharePoint 2010 workflow blank email question

I have a workflow tied to a calendar that fires when an event is added to the calendar. The workflow sends an email 7 and 3 days before the event startdate.

I am having a problem where users are getting a properly constructed email and one in which the lookup fields from the list are blank

Example Correct email:

Subject: REMINDER - renew domain address @ 1/29/2014

Problematic email

Subject: Reminder -  @ 1/1/0001

I have checked my workflow for an extra send email command and there isn't one. What would cause the workflow to send multiple emails on of which retreives nothing for the lookup fields?

Mike