eregi_relace() and HTML <map>

Hi list, I've got a really strange problem : I will try to explain with my poor English. On one hand, I've got an HTML page whit something like this (*) to declare a map ( this code was generate with Golive by a friend ) and only one beacon named <index>. I use the function eregi_replace to display the page and replace the beacon by an URL with session_id(). This page is the first of a session, so it contains session-name("MySession"); and session_start();. My problem now : When I open a browser ( and only when I open it for the first time ) the source is transformed and '?MySession=9e76ffcd24c8fa57f5e8f1096a1493e9"#" coords="55,65,86,78" shape="rect........' appears a couple of times on source and on the page. I really don't know where can it come from. If someone's got an answer, it should be welcome. Thanks for all. Pierre. (*) = <img height="88" width="168" src="img/t1menu.gif" border="0" usemap="#logomenuXXX137e3c13"><map name="logomenuXXX137e3c13"><area href="#" coords="55,65,86,78" shape="rect"><area href="#" coords="52,49,95,62" shape="rect"><area href="#" coords="28,34,109,47" shape="rect"><area href="#" coords="37,15,127,28" shape="rect"></map></td>