Firstly, I just tried converting a 10.5 MB Word file, and I had no problem, if nothing else, you can share the Word document with me, and I can give you a link back to your new PDF document?
It might be just a bug. It might be an overload, especially if you are uploading them all at once. Maybe try the other documents, and the 9.4MB one last, after all the others have been safely converted, and you can see them.
-Alex