I didn't knew of the bluefire reader, ok, I don't know about a lot ! I just use Moon+Reader for my Android, and the integrated reader of Sigil, my ebooks file editor.
And I can say, he is pretty good ! (at least for the windows version) .. ok, I just tested it like 30s, but it looked good. (some features like the number of columns adaptation were cool, and others like the lack of focus on dialogs were annoying. but hey, can't have everything).
The reason I'm talking about this reader is thankful to the report of someone (yes, it's the name he signed, too bad, the mail informations informed me it was actually Aladeanra).
My ebooks (nearly all) made Bluefire crash ! Yup, my files are this powerful 8D
Actually, it's just one code line (css) used to make the text on covers to be centered on the page, and when a css isn't supported by a reader, it should ignore it, but Bluefire really didn't liked this one and crashed ... not good.
For the time being, all .epubs have been edited and are now Bluefire-crash-free, with a little addition on covers. I think they are a little better.
In the same time, I have mailed Bluefire to warn them of this bug so they can patch it.
Thank you Aladeanra for noticing me. (and Bluefire will probably thank you by proxy)