How do I resolve this error "the jpeg you have selected was saved in a non standard format"?|PS3 Themes|Forum|PS3 Themes

I downloaded jpeg files from the internet

I them resized, cropped and manipulated them using gimp

I exported file to jpeg

the size is under 1mb, the dimensions are 1920x180

when I try to add them I get

"the jpeg you have selected was saved in a non standard format"

I can reopen these files in gimp, there doesn't seem to be any additional options when exporting to jpeg

I spent the day on this so please help salvage my work I can't tell you how disappointed I was when I got the error

what should I do?