I've never experienced this problem, but I would guess it might be down to the fact that if you click on the area surrounding the link (when it highlights to a lighter shade of grey), that also takes you to the first page of the post. So perhaps your browser is confusing the link with the background and the background link (i.e. the javascript:document.location.href bit) takes precedence? It's the only reason I can think of, although I don't have a problem in Mozilla 1.5 on Windows.