Building on Dr Doug's reply ... this is a File Type and File Creator problem. I suggest File Buddy ... see the pargraph below:

If you are having trouble getting the File Type and File Creator and you want then download a utility like File Buddy (see shareware.com) which will give you control of type and creator. An example might be if you want your mp3's to be iTunes files and you're getting QuickTime files you can use File Buddy to change the File Creator to iTunes.