Originally Posted by theducks
2 things come to mind:
1) a recently added font is corrupt/the font Calibre was using was removed.
2)you have corrupted the settings.
Preferences: Miscellaneous: click the button labeled Configuration Folder..
Leave the folder OPEN and Exit Calibre.
Delete the folder (and contents)
Uninstall Calibre,then Reboot
yes to # 1 ..it happened after I updated...told my mom I should have stuck with my "if it aint broke don't fix it" rule of computing ...made sure she never up dates here ,,
I will try your second suggestion ...and Helens if it doesn't work ..
I have a LARGE number of books to convert from epub to mobi,,,just like this program ..would be a shame to have to use another