I am having a similar problem on Windows. I create audio mp3 files for radio on a program called Virtual DJ. I then edit them on Wavepad. I have been doing this for about a year, consistently, with no problems. Then all of a sudden today I got error messages as I tried to open a particular file. First I got a window with a red X error message on it saying that it could not open the file. After several failed attempts with the same result, I restarted my computer and I was able to open the file. But when I tried to open another file, I got another error message -- this time with no red window but with a simple message stating: "Wavepad could not open the file "[file location]" for editing." But this only happened with the new files I created today. I tried opening older files and had no difficulty. The new files had the same program, same basic content (voice and music) and approximate lengths as before -- nothing I haven't done literally hundreds of times before, but all of a sudden, Wavepad is not opening newly created files.
Any suggestions, please? I use this for radio productions. It's a great product, I just want it to work as before.