This is a long shot but try it, keep us posted
The Normal.dot template file used by Word might be corrupt.
To rename the Normal.dot file follow these steps:
1. Quit all instances of Word, including WordMail.
2. On the Windows taskbar, click Start, point to Find, and click Files or Folders.
3. In the Named box, type Normal.dot.
4. In the Look In box, select your local hard disk drive (or an alternate user template location if you are running Word from a network server).
5. Click Find Now to search for the file.
6. For each occurrence of Normal.dot that appears in the Find dialog box, right-click the file. Click Rename on the shortcut menu. Give the file a new name, such as OldNormal.dot or Normal-1.dot.
7. Minimize the find dialog box.
8. Restart your automation client to start Word.
A corrupt global template causes errors when automating Word