Hey Lauren,

I am sorry that delay of this reply,

I have help you solved this, can you try authenticate with your Facebook account again from Easyblog Facebook autopost configuration page and see how it goes?

If the error still persists, can you provide us with your Facebook access as well?

thanks. Now I'm getting a different error when I log into Facebook:

Hey Lauren,

When you hitting this following error, it actually come from your server mod_security issues, can you consult with your webhosting provider regarding this or perhaps you have temporary disable this mod_security from your .htaccess file and see how it goes?

An appropriate representation of the requested could not be found on this server. This error was generated by Mod_security in facebook 

Reference link : http://www.simplemachines.org/community/index.php?topic=512056.0