PS CS: Why Does JPEG "Format Options" Sometimes Default to Progressive?

For reasons I have been unable to fathom, the JPEG Options Dialog box often presents with Progressive selected in Format Options, even though I always change the choice to Baseline ("Standard") before I save as a JPEG. This is in Photoshop CS, and occurs frequently, but not every time I open Photoshop.

I realize this cannot be by design, but I have been unable to (a) understand why it is happening, and (b)find a setting to change the default behavior. I have searched the FAQ, Adobe forums, PS Help, the User Guide and Google and remain ignorant.

Bob N.

Have you been using any scripts that save as jpeg? I'll elaborate if your answer is yes.

No, I've used no scripts.

Bob N.