I made changes to an existing word document but cannot save and close.

Specifically:
I copy and pasted (as pictures) two selections from an excel spreadsheet. I selected save from the drop down menu and then tried to close the document. Instead of closing the doc, Word gives me a message window that asks if I want to save changes. I select yes and the message window closes but comes back immediately when i try again to close. The only way i can close the document is if I choose don't save.

The same thing happens regardless of what kind of changes I make.

This document is mostly a series of tables with several sections of excel pasted in as pictures. Does anyone know what is going on? I have several nearly identical documents that i just modified and they do not behave this way.