The error message that you are seeing means that there is a line in your glossary that has some type of error on it. Fortunately this is an easy fix with the help of the Glossary Workshop! :)
The Glossary Workshop can be found by right-clicking in the Phrases Advisory, select "Importer" and then click on the "Glossary Workshop" tab. There you will see a "Repair Glossary" button. Click on that and select the glossary that needs to be repaired. Once the repairs have been completed, select "OK". Then close out of the Workshop window. Instant Text will then ask you if you want to save the changes made to the glossary, select "Yes" then save the new glossary.
For more information on the Glossary Workshop, please see page 75 of the manual. Page 78 discusses the Repair Glossary feature.