I am posting this to make people aware of the following issue I had and resolved:
1) Was unable to load a picture via the Featured Post widget for a Product
2) Was also unable to open the Media Library via the Featured Post widget in Product
This was finally resolved when I disabled the WP Smush.it plugin supplied by Yahoo!
Appears this plugin does not work as smoothly with the latest version of Wrodpress.
Have been using this plugin for many years, hopefully Yahoo! will update it to work with the latest version of Wrodpress.
Hope this has helped save someone time and very interested to hear from anyone that has this plugin installed with the latest Wordpress and Marketpress versions installed.