how do you access the first page (page1.php)? by a link or by a form submit?
if you access the page the first page by a form, you can add the headers i posted before. if the user hits the back-button, a message will be displayed telling them that the page needs to be refreshed!
so, access to page1.php would look like:
<form action="page1.php" target="_self" method="post">
<INPUT TYPE="image" VALUE="anyvalue" NAME="anyname" src="anyimage">
</form>
just create an image which will displayed as link to the new site.
on page1.php you can make a test, if the user (check IP) has already visited this page or just send him the blank page.
hth