I am working in Office 2003 and have the Office 2007 compatibility pack installed. I am receiving docx files from my co-workers and then making changes to those documents and emailing them back to my co-workers. Once I save the changes to the docx files a dialog box pops up and says " *.docx may contain features that are not compatible with Word 2007 Document format. Do you want to save the document in this format?" Are all of my changes getting saved? Which featurres are they talking about here?