Since this answer seems hard to come by, I'm posing both a question and an answer.

I've been using Magix movie edit  pro 15 for years now, with the same computer, same OS (Win 7), and the same HD camera.  Then suddenly I started getting this error when trying to import or batch convert  the camera's AVCHD (.MTS) files;

The file format of <filename> cannot be read!

Please make sure the drive is not full or write-protected. If you do not have the authorization to write or read from this path, please contact the administrator

After trying everything I could think of (short of throwing my computer out the window), I finally found an answer. Turns out that if you rename (or delete) the MovieEdit.ini file all your problems will be solved.  Well at least this problem will be solved.  The file is located in your AppData folder:

C:\Users\<username>\AppData\Roaming\MAGIX\Movie_Edit_Pro_15_Plus\MovieEdit.ini

I hope this helps someone else.

-Ricardo