What it sounds like is that you have your system set up so that recognized file extensions are hidden. What you will need to do is open an Explorer window, select the menu option, Tools, then Folder Options. When that opens, select the View tab and scroll down until you see something that reads, Hide File extensions for known file types, and remove the check mark beside it. Close the dialogue box and you should see the file extensions appear. If for some reason you don't, close the Explorer window and open another one. That should do it.
Hope this helps.
Jeff Foster, PE
CE Group, Inc.
Apex, NC