Using Prism Mac, I can't  open the files by double-clicking on them.

When you double-click on a Prism file, Prism ought to be launched. Instead you see the message: " Unable to open file. It may have been moved or deleted, or you may be low on memory or disk space. "

Prism 4 Mac. We know this can occur when you use Kanji (Japanese) or other two-byte fonts in the file name.  The work arounds for now are to either avoid Japanese characters in file names or always put your files on the desktop (where they should open fine), rather than in a folder. And, of course, you can open the files using Prism's File Open menu. We fixed this bug in release 4.0b, so update if you haven't already.

Prism 3 Mac. This can happen when the entire "path" and file name exceeds 219 characters. Workarounds are to use shorter folder names, use a less nested folder, or save to the desktop directly.