Bernardo,
The issue seems to still be the same. The problem (I think/hope) is that there's a tag missing in the <html> declaration of your site. The JFBC System plugin should be adding it, but I'm still not seeing it on your page. Can you clear your cache and try again? What we're looking for is that your html tag should look like below:
<html xmlns:fb="
www.facebook.com/2008/fbml" ....
You can look at how it looks on this site as well, for reference. If clearing the cache doesn't work, and the JFBCConnect System plugin is published, my next suggestion would be to manually add that tag to your template's index.php file. It shouldn't be hard, but never like forcing people to edit code more than they have to.
If you could try that, and report back, we'd love to hear your results. I really do think this is the problem, but if it isn't, we'll get to the bottom of it one way or another!
Login button not working
Button is still not displayed in IE the first time around. 
