Images not loading in internet explorer
Sometimes JPEG files will not load in Internet Explorer and will instead just display a red x while other browsers load the image perfectly.
Before you start searching through your code for errors, try this. Open the image in paint on Windows or preview will do on a mac and just save the file, upload it again and you may find it just starts working.
The reason for this is that Internet Explorer gets confused when it finds extra XML data inside JPEG files and refuses to load them. Programs that may add XML to your JPEGs I know of are Photoshop, Illustrator and iPhoto.
:)