Everything was fine until a recent disruption in service. My guess is they restored a backup to the server and that had gotten corrupt. Still, I reloaded some files via ftp (yes, Binary mode) and they still give download problems.
One thing I found was that if I right click and did SAVE LINK AS, I had better luck than just clicking on the file itself.
Let me know if there are specific ones you want, I probably have them on my system and can mail them to you.