I need a destructive image edit because wordpress non-destructivley edited images won't work with my feed. So I was happy to find PHP Image Editor Lite. Actually, all I need to do is crop black bars from thumbnails imported from YouTube, and this plugin solved the problem. Then, all of a sudden, when I went to crop a featured image from the post page, I got a message "Image does not exist". Work around was to go into Media library from the dashboard instead of from the post page. That worked for a few weeks, then all of a sudden when I clicked on the edit button, all I would get is a blank white window.