Thanks for the reply.
I have never used Calibre before so I would not expect a previous library. OS is XP. The version is whatever is the the most current as of Nov 25, 2010.
I did have some ebooks in a folder labeled My ebooks. They are in pdf format. Not sure if that matters. Also when I first launched Calibre it seemed to be going through a process of building a library b y examining every folder. Since I did not have any books, I canceled the process.
I did uninstall and then reinstall but received the same error message.