Dead product Rated 1 out of 5 stars

OpenBerg Lector has been abandoned for years, and the home page for the software is now in the hands of a click harvester. I'd give it no stars, but Addons won't let me do that.

People interested in reading ePub files in Firefox should look at EPUBReader, at
https://addons.mozilla.org/en-US/firefox/addon/epubreader/

That one works fine here under FF 3.6 and 4.0, and I use it to read locally stored ePub content with file://<path to file>