Unable to save documents, but have storage space

I have a MacBook Pro with 2.7GHz intel core i5. It is using OS X El Capitan version 10.11.3. I attempted to save a document on word, when I did a message came up saying that it was unable save or create this file as the disk may be full or write-protected. I checked my storage space and it isn't full. I have tried repeatedly to save the document, but am unable to do this. I tried to save a different document and I encountered the same problem. I was wondering if anyone would be able to help me try and resolve this problem?

Thanks

Matt