I had th same problem in 2.8.4. I thought that with 2.8.5 it will be gone but i thought wrong.
I’ve tried timclark’s method of setting permissions, deleting and re-uploading fresh wp-admin and wp-includes but no luck. It still doesn’t work.
So far the only thing that helped was Dean’s FCKEditor For WordPress plugin.
Hope that in the near future someoane will save us :))
I forgot to thell that nextGen started the problem in the first place fo me too.
