It was a html error... or is it ?. in any case it is solved.
Here is the code responsible for it
<div id="headinner" style="position:absolute; left:49.9%; margin-left:-1000px; top:0px; width:2000px; height:136px">
I had to put "left:49.9%" instead of "left:50%" to fix the image...
Since when Dreamweaver is like that ? seriously ? 49.9 % or 50.1 % but not 50 % ? is it a bad joke ?
Why are you absolutely positioning that in the first place?
Because it's a header and the website is designed for 1024x768 - 1920x1080 and because the image have a different left and right side, thus not allowing the classic method to make a liquid layer. And also because it need to print, so no background.
The probleme stay the same without the absolute positionning