Yeah, I spent ages trying to work this one out. I was using an image uploader in the backend of X-Cart 4.3.2 to transfer client-supplied images from my PC to their website for an ecommerce catalogue and the images all displayed fine in Firefox, but a couple were missing from IE.
I figured it was an issue with X-Cart but it wasn’t. The images that weren’t showing in IE were actually slightly corrupt (or perhaps CMYK images, who knows) and although IE wouldn’t actually tell me this, the really simple fix was to open the original images supplied by the client in Photoshop, resave them (Save for web > jpeg) and re-upload them via X-Cart’s new (as of v 4.3.2 anyway) image uploader in the admin.
Hey presto, the images are visible in IE.
So, if you have a problem where certain images are visible in Firefox but not IE, chances are you need to re-generate the images via an image editing tool (in my case Photoshop) and re-upload to your server.
Worked for me, anyway.