Originally Posted by shadow_hk 
Thank you for the effort but the problem seems to persist..

I'm using Firefox 3.0.4 and I have deleted all browser cache..
Strange, it works for me since the fix. Maybe you could try
changing your options (miscellaneous at the bottom). Set your "Message Editor Interface" to standard, save, then change it back to wysiwyg.
Or maybe you have some custom styles that are interfering somehow? Greasemonkey, AdBlock element hiding helper or something like that?