We have never seen the "Corrupted image" message that you're getting, and are a bit stumped as to what could be going on. Do you have any anti-scraping tools or security extensions that try to prevent bots from scraping your site? It's my only guess as to what's going on, but I can't find any details on what that error could mean otherwise.
The only other thing that stands out, though shouldn't matter, is that the file ends with a capital JPG. You can try lowering that as it's more common, but again, I can't imagine Facebook cares...
We'll keep investigating, but if you find anything, please let us know.
Thanks,
Alex