Thank you Charles.

- I opened Word in safe mode > same issue !
- then I renamed all building block files I found in the roaming directory (c:\Users\{your username}\AppData\Roaming\Microsoft\Document Building Blocks) > same issue !
... do you have another suggestion ?

The document I am working on is indeed a very large file with headers and footers and about a week ago when saving and exiting Word I was surprised to see a message asking me if yes or no I would like to save or not building blocks. Working with Word already for a long time I never saw that message before and as I was afraid to loose all of my work I agreed to save the blocks... perhaps doing so caused the probem ???

Do you have another suggestion for me ?