Just tested this in my server using news j3.0 quickstart package > installing jce > updating to joomla 3.1.1 from control panel all working fine.
Uploaded image fine.
Page breaker works fine while using jce as editor plugin.
Perhaps something went wrong during your update such as some of the files did not upload properly.
Try manual update.
http://www.joomla.org/announcements/rel ... eased.htmlLet us know how you get on, see you around...