Dear Sam

I've changed the code in de .ascx file. The following code

IconFile="<%= SkinPath %>Xml.gif" gives the same error
IconFile="<%= SkinPath %>Print.gif" gives the same error
IconFile="<%= SkinPath %>Max.gif" gives no error but now I can't see the Max.gif (I see the replacement square)
IconFile="<%= SkinPath %>Xml.gif" gives no error but now I can't see the Min.gif (I see the replacement square)

dnn runs in the following root:
http://localhost:2118/dnn403/Default.aspx,
I think that looks normal and the files are located in
Disk-Mijn documenten (F:)
 VisualStudio2005
  dnn403
Can that be a reason?...

Come to think of it, I'm not so sure that suggesting the <%= SkinPath %> directive was correct, since you have these images in the container folder, not the skin folder. 

If I were using custom icons in a container as part of a skin package, I might put the images in the skin folder though, so that I could use the skinpath directive.  On the other hand, if the container was for a site I had full control over, I might hard-code the paths to the images instead.

Hope I haven't confused the issue even more...