If you've used Name Mangler to rename a bunch of image files (any files, really, but this happens most often with image files) and are shocked to find that they all now list themselves as "Unix executable" files in Finder—and won't open—here's what you need to do:
What's happened is that your images have lost their filename extension; this can happen when you uncheck this box, which appears in (many of) Name Mangler's renaming modes:
When that box isn't checked, Name Mangler will remove the filename extensions, resulting in the unusable files you currently have. The fix, though, is simple (assuming all files originally had the same extension): Drag the batch of 'bad' files into Name Mangler's rename area, set the Select Task pop-up to Set Extension, then type the extension you'd like to add. Don't type the period in front of the extension, just the three-lett extension. Click Rename, and you're done.
If the files weren't originally all the same type, you have a tougher task ahead of you. You'll need to drag in only those files of the same type, rename them, then repeat for the next type.
We realize this isn't an ideal situation, and a future release of Name Mangler will include a strong warning screen if you ask Name Mangler to remove filename extensions.