See below
I recently changed to Firebox from I.E. I was also compelled recently to switch to "new " Yahoo Mail. I can no longer open email image attachments in Photoshop. I can only low grade images in a slideshow box. If I try download and open n Photoshop it says cannot be opened unless I buy unzip program. Before I changed to Firebox and "New" Yahoo Mail I had no problem.
Opaite Mbohovái (1)
It sounds like you are downloading a zip file. You need to extract the files first, then open in Photoshop. You can extract the zip for free with Windows. Just right click, and choose extract all. Then open the picture from the extracted folder