Weird. My error message disappeared. Now the editor works fine in both FF and IE. I suggest: turn off the option to use the rich text editor under user preferences, clean the cache of your preferred browser and then restart the browser and try editing a post. Turn the option back on again, and see if you still get the message. That’s about what I did.
I’ve got the same problem. The “TinyMCE”-part means that it’s the rich text editor that causes this, and if I turn off the rich text editing I don’t get the error. Also, the error only shows up in Firefox 1.5, not in IE 6.0. In IE I can use the rich text editor without any problems. Which browser are you using when you get the error?
