Steps to reproduce:
- Using Firefox 3.6 on Windows (haven't tested anything else), start a conversation with someone
- Go to the new conversation
- Use the toolbar button to switch to the standard editor - it will work fine
- Refresh the page (using just F5, not Ctrl+F5)
- Try to use the standard editor button again - AJAX loading indicator appears and disappears, but the WYSIWYG editor remains in place.