Can't open images

I am trying to upload 24 images to Zillow and Craigslist. Both won't allow me to upload about 1/2 the images; Zillow seems to allow more than CL. When I try to open them in Fireworks, that ones that the listings won't upload are saying: "Could not open the file. Unknown file type."

All images are the same dimensions, about the same size and all are jpgs!

I did save as for all of them from a listing client has on AirBnB. But it that were the problem, why wouldn't all of them have a hard time opening in Fireworks?

Thanks so much in advance for your help!