Thanks Diva Vocals for starting this thread. I too have had problems recently that I can't solve and it's been very difficult finding info.
The most recent problem developed on a dual language site when we upgraded to 1.5.1 and moved to a new server. No ckeditor boxes show up except in ezpages where I have the multi-language ezpages installed and even there only one box is showing.
I am using the most recent version of ckeditor and the database has been converted to UTF-8. Admin is not secure. I am clueless. As this is a javascript editor, server settings should not be a problem, I assume. But I think all was okay after the upgrade but have no proof now.
The plain text does show the html.