lol is this your site its just you dont seem to know it too well? just take the session id out of your URL's on the hompage (they are not on the other pages).
Code:
<li><a href="/add-contractors.html?PHPSESSID=46556c1ba49c38a1beebe2ebb2531d2a">Add Contractors</a></li>
should be
Code:
<li><a href="/add-contractors.html">Add Contractors</a></li>