Discovered there was something wrong with the ePub versions of my short stories. Calibre was giving me an error message when I tried to convert to other formats. I think I figured out what was wrong. Removed one line from the content.opf file in the ePub file. If that makes any sense. It has to do with the fact that an ePub file is actually a .zip archive with the file extension changed from .zip to .epub. It's why you need a program like Sigil in order to edit the .epub file. Well, you can probably open the .epub yourself simply by changing the extension back to .zip and unzipping it, but that's more annoying even than I want to deal with. Sigil is an awersome program, by the way. Calibre is awesome, too, by the way. It's just not an ePub editor.