The URLs are subtly different.
The first, which failed when using the IMG tags, is:
http://www.pbase.com/ninaludwig/image/1 ... large.jpegThe second, successful one is:
http://www.pbase.com/ninaludwig/image/1 ... /large.jpgRather than being an intermittent problem, it would seem that the extra "e" in the file extension name is critical.
We need to let Peter sort out why this anomaly is occurring, but it would seem that you have a workaround to the difficulties you have been experiencing when embedding your images in a forum post.