In a folder of JPG files, Windows XP has a "Filmstrip" option. Why is it only available some of the time?

Question

Under the View menu or the Toolbar, I've noticed that sometimes there is a "Filmstrip" option but most of the time my only choice is "Thumbnails". How do I get it to give me the Filmstrip option?

Answer 1

All the pictures need to be in a picture only file, if there is anything else in the file, it wont allow you to view a filmstrip.