Originally Posted by Mrgauth
Don't see Mobi as an optionn in the output drop down either. Only choices when going from epub (input) is
fb2, lit, lrf, pdb, pdf, rb, rtf, tcr, and txt
That's it. In the upper right corner is what output you want to convert your book to and prc nor mobi is a choice. Now what?
You're missing mobi and pmlz from your output options.
If you are running Windows then I would try uninstalling Calibre then look for and delete (if they exist) the following two directories c:\program Files\calibre and c:\Program Files\calibre2. Reboot your computer. Then reinstall calibre.
As long as your library is not a sub-directory of the directories I suggested deleting then your library and your settings should remain safe.