Never mind, the user deleted the bmp image and replaced it with a jpeg. Problem solved

I'm having a problem similar to what rhyang described: when I try to visit the thumb link (or any size of picture) of a file ending in .JPG, it gives me the download box. Images that end in lower case .jpg work just fine - this is kind of annoying, as I'm trying to post some thumb images into some tables on a page and I can't get those pages to load! This image is one example: http://www.summitpost.org/image/318176/317218/jupiter-peak.html

OK - the thumb pics appear in the tables by typing the correct address into the code, but the actual address itself won't open and it gives the download box.