I installed and activated the most recent version of FCKEditor (2.4.3) on a fresh installation of WordPress 2.5.1
The write page seems to load most of the functionality, but continues indicating that it is loading and eventually times out / locks up. I did notice that the actual text box where you can add media does not activate a cursor when rolling over.
Is this a known compatibility issue with FCKEditor 2.4.3 and WP 2.5.1 or am I missing something? I saw a few comment posts on Dean's website that described the same behavior, but nothing in the documentation here at WP.org
Any feedback would be greatly appreciated!