I fear I cannot help, I have no knowledge about waht mod_pagespeed does (I admit I didn't even know about that until now). There are two things in the URL reported I don't understand:
- If the domain is yours, the `mod_pagespeed` part must be the fiolder Zenphoto is installed in. Otherwise iwill not work. (domain/mod_pagespeed/someimage.jpg.html would be a image page URL if the rewrite suffix is set as ".htm").
- The URL query at the end clearly does not belong to Zenphoto.
I can only assume that mod_pagespeed is causing the issue here for some reason. Sadly I don't have that extension available on my servers so I cannot test it at all