Did some digging and found the issue with Firefox losing the EnableObjectResizing property can be replicated on a demo page.
http://richtextbox.com/test/EnableObjectResizing.aspx
When you first load the page you cannot resize any of the objects in the CE box, but once you fit to window it drops it and you can resize everything. Then when you restore back to normal, you still can resize.
Any way to avoid this happening? Seems to be Firefox only...