Right click on a broken image and go to properties. Copy and paste the link to the image in a new IE window and see what happens. For example if I right click on your sig and go to properties I get: http://img.photobucket.com/albums/v114/jeller/Jellersig.jpg
When I get broken images here at work I do that and a lot of times they are being blocked by the firewall. At a minimum you should get a more descriptive error.