Not really a bug; but you might want to allow for recognizing malformed/incomplete mobi's. I was experimenting with delivering mobi's from a webserver and ended up with mobi file fragments on my hard-drive. Whenever I browsed to folders (fileOpen dialog) that contained one of these mobi "fragments" using K4PC or KindlePreviewer, both applications immediately crashed. I couldn't figure out what was going on at first, but as soon as I uninstalled MobiHandler, I could then browse to those folders without K4PC or KindlePreviewer crashing on me.
It might not ever affect anyone really, but I thought you should know.
