It looks like our Server Admin, Sean, fixed it! I uploaded a test image at it's native resolution (I didn't have to resize it at all) and it worked! Have a look!
http://www.joedios.com/dioramas/sho...php?i=28740&c=7
The problem was the image resizing program on the server side wasn't working properly, so he switched to a different program that is working fine.
Thank you Sean!