I am currently using WordPress 2.1.2. I am having these problems in Firefox 22.214.171.124 and IE7 on Windows XP.
For a little while now, I have been having some problems with the rich text editor on one of my WP installs. When pressing enter (to end a paragraph and start a new one), the editor actually inserts three paragraph breaks.
Also, most of the other buttons are messing up as well. The unordered list button looks to insert a bullet, but then erases it automatically. When inserting a link, I can use the dialog box, but after clicking insert (and the editor correctly inserting a link) the dialog box clears but does not close.
I have seen several posts about this, so I cleared my cache. This didn't work. Then I recopied over the wp-includes files, and this didn't work (I recopied and cleared the cache).
Any ideas would be helpful. Thanks!