[federalbetrayal]

I recently began using Calibre to convert PDF's to Mobi files to increasing readability. Most of my files worked, but a few did not. Calibre simply "failed" to covert them, and I tried them again and again. Is there a way to jailbreak them so I can convert? (there are no copyright issues, the authors of each were from the 19th Century and I got them for free on the internet from academic institutions, thus avoiding all intellectual property restrictions).