The Windows security update (KB973904), released on December 8, 2009, changed the way that Windows and third-party components use the WordPad-to-Word 6.0 converter.

Microsoft has issued a utility to address this issue.  Go to Microsoft Knowledge Base article 973904 to download and run Microsoft Fix it 50352.
 

Note: We provide links to third-party websites in an effort to help you resolve your issue. We are not responsible for the information on third-party websites, and we cannot assist in implementing the solution on these websites.

Try each of these steps until the issue is resolved:
 

  1. If you have Microsoft Office 2007, Service Pack 2 installed, and Microsoft Security Update KB973904 has been applied, that may be the cause of this error (among others) when performing mail merges.  Follow these steps to resolve this issue. (BB708164)
  2. Close all open Microsoft Word instances. Reopen the merge document and merge again.
  3. Save the document to a different hard drive. 
  4. If the Mail Merge is a Conditional Merge, open each letter in the merge to see if any of them are corrupt.  Delete any corrupt letters. 
  5. Recreate the query from scratch (BB19082)  using the same filters as the problem query. Use this query instead.
  6. Update/repair the workstation. (BB57039)
  7. Uninstall and reinstall The Raiser’s Edge or Education Edge on the workstation. (BB57039)