Box with red x instead of graphic

Ok… I have been using iWeb and love it, but why when I place an image inline with text. I did what apple says to do:

Choose Insert > Choose, select the file, and click Insert. To make the object inline, place the insertion point where you want the image to appear before you choose Insert. To make the object fixed, click outside the text boxes so that no insertion point is visible before you choose Insert.

I get the dreaded box with a red x inside (PC) or a blue box with a ? in it?

I want to have an image beside the text and have a file (a PDF) link to it for my parents to download, read or print. The only way I have been able to get it to work (were the red x is replaced with the correct image) is to MASK the image. What a PAIN!

I have used a .gif, .png, .jpg and they all give the box with a red x. Please help.

Go here to see the problem. http://www.christianlifeprep.org/CLPS/Documents.html

Again I have fixed the issue with a mask on the image, but you can see on the page that I have left other images un-masked to show the issue.

Oh. The image is a blue box with a question mark on my mac and a box with the red x on the school PC (running IE 6)

PLEASE HELP