We are sorry to hear that you have this issue. We need more details in order to successfully reproduce and investigate this bug. In particular:
1) Can you send us the Word document, using which, this error occurs?
2) Can you post a source code of the GroupDocs.Viewer widget, so we will be able to see, which options and features are applied when displaying the document.
For maximum convenience you can post the code and the document in this forum thread. Just make it private (“Make Private” button), attach the file inside the ZIP archive and post the source code as a simple text.
Thanks and waiting for your reply.