Apparently there's some "erratum-not-bug" in some Athlons that makes something go wrong with some specific JPEG-encoded pictures. Dunno what's supposed to happen, if they just don't display correctly or if a visit from the Doctor is the usual consequence... But if it was an AMD-CPU box, you might want to look into that.
Sorry I can't be more specific off the cuff, but what's the use of me Googling for stuff when I don't even know yet if it was an AMD box, and you can as well Google for it yourself, if it was.