Close Button is missing, but hyperlink is there

Hi there,
it looks like my lightbox is not viewing the close-button.
If you hover the mouse over the position where it should be, it changes to a hand and the hyperlink is also working.
So the functionality is working.
Here is the link to my demo-page : http://www.tooren-beer.ch/cms2/image/tid/2

I did not change anything of the code.
When I'm using the FF it is not showing the button.
When I'm using the IE it is showing the red cross (="image not found").

gb5256