Hey ogre et. al.! Maybe this brief note will be redundant, but I'll put on my "two cents" worth anyway because I had a similar problem when I first downloaded songs in ZIP format and then tried to open them in my 7000. Always got the message that, after loading (I thought), "the file was empty"! Someone on this Forum helped me out (as always!!)
So, I learned that the steps are--(assuming you are using Windows on your PC):
1) Click on the ZIP icon in your message.
2) Your unzip program (I use WINZIP) should automatically open. Follow the instructions for unzipping.
3) After the file is unzipped, a window with icons for all the unzipped items appears, (there should be 6-8 individual files listed).
4) Click on the EDIT button at the top and, in the drop down window, click "Select All". (The unzipped file icons should darken.)
5) COPY the files to your floppy disk (or MOVE them--I prefer to copy because then I still have the original files saved).
6) Close your ZIP program (or minimize it if you have other files to unzip) and then check your floppy (click "START", then "RUN" and insert "A://" ( or whatever letter your floppy disk drive is)) to see if all has indeed been copied. (If so, you should get a window that looks just like the original unzipped window that you copied.)
7)Once you have verified the unzipped files are opened on you floppy, you should be able to take the floppy to your 7000 and load it and it should playable.
I think what you were doing is trying to load a FOLDER, rather than the opened unzipped individual files and, of course, the 7000 couldn't read it. So, the message, after loading, was that the file was empty.
I hope this makes sense to you. I never have had any problem loading the unzipped songs since learning the techniques I described above and I hope this is will help you, too, now!