sorry, I can see the problem now.
I don;t know what the cause is, but when I see the link from the way you just described, there is an extra slash in the url path.
Instead of reading
<a href="/products_results.php?pageNum_WADAProducts=1&totalRows_WADAProducts=28&Search=1&ProductCategoryID[]=7">Successivo</a>
it reads
<a href="//products_results.php?pageNum_WADAProducts=1&totalRows_WADAProducts=28&Search=1&ProductCategoryID[]=7">Successivo</a>
the same is true for the 'ultimo' link