OK. The suffix is part of the name. Shakespeare wrote:
"That which we call a rose by any other name would smell as sweet." This means that changing the name does not change the file type. There are, however, some applications that explicitly handle different extensions differently. GUI-based operating systems often use the extension to associate files with applications. The extension is one [but not the only] criteria used by MacOS X. It sounds like your files are improperly associated:
- Within the Finder, select a traditional Word .doc file.
- Select File/Get Info.
- Locate the Opens with: popup menu.
- Select Microsoft Word.
- Press Change All....
- Repeat Steps 1 through 5 with an XML-based Word .docx file.
- Repeat Steps 1 through 6 with Excel and PowerPoint files.
There are special circumstances. However, the only non-special circumstance that calls for changing the extension is when
Safari or some other application explicitly appends an extension to a downloaded file. In such a case, it is OK to remove the appended extension.