It sound like your EZ Update may have updated your Navigator Application and now looking for a newer disc.
You will need to go to the Navigator Repair Tools to revert your application to read the current disc:
Please go to the Start Menu/All Program/ATP/ATP/NavigatorV/Repair Tool
Under the Content Repair, click on the Reinstall button. It will prompt you to insert your current white DVD disc
Once completed open your ATP Navigator and go to the EZ Update tab and click Install Content to load the specific library disc.