Cant convert word doc’s to PDF format

I am using acrobat ( full version) and I convert my word docs to pdf format for our web site. All of a sudden, when I try and open my word document, acrobat says can not open the file because its not a supported file type or the file is corrupt, however I know this is not the case.

I have been opening word doc’s for over a year with this program and converting them to PDF, any idea what has gone wrong?