I don't remember doing anything with any particular ID (although I did play around with one image, changing settings by ID to see what effect it had).
I've had to dash out to work but just before I left, I did try changing it from 200px to 500px. But to no avail. So I simply did a search and change to 500px to see what would happen. Still no joy. This sucka won't go down..

But when I return home, I'll have a good slug of coffee and see what's what. It's got to be some kind of global setting as this width thing is affecting all pictures.