Users Settings > Adding Files tab > File extensions

In the ePDM Admin tool, when you right-click on Users, go to Settings, go to Adding Files tab....  Is there ever anything that could change the list of file extensions, other than actually going in there & manually editing them?

I had a problem the other day where there were '.' added in front of each, where they are not allowed. 

So for example, the list looked like this:  .doc;.docx;.prt;       where it should look like this:  doc;docx;prt;

Just wondering if there is some other connection to these file extensions that I'm not aware of...