Sometimes when you open a palette, Color Palette Editor may be unable to detect the exact format, for example 18-bit VGA, 24-bit VGA and Adobe Color Table formats are identical, but can appear quite different if read incorrectly. Color Palette Editor will prompt on how to open the file if it finds multiple matches.
Click the Preview button to expand the dialogue to include a preview pane. When selecting a format from the list, the preview pane will be automatically populated with the result of opening the palette used the selected format.