[jQuery] Image-Offset problem

Hey.
I have a strange problem with image-offset.
When I open my page by typing url, my $("#image").offset().left is
640px.
But when I go to the exactly same page with a link (<a href...) the
offset changes to 570px.
Any idea, what it could be?
The problem occurs in Chrome 4 and Opera 9. In Firefox 3 and Internet-
Explorer 9 everything is perfekt :-/ .
Doctype: XHTML 1.0 Transitional
Thanx!