Different postback URL being generated

Question

I have got two machines and one of them when I navigate to a page, the postback URL looks something like this:

<form name="aspnetForm" method="post" action="./page.aspx?Action=nav&amp;Page=4577" id="aspnetForm" enctype="multipart/form-data" autocomplete="off">

But on another machine, the same code renders a postback url without the "./" in the action attribute:

<form name="aspnetForm" method="post" action="page.aspx?Action=nav&amp;Page=4577" id="aspnetForm" enctype="multipart/form-data" autocomplete="off">

Any ideas what could be different?

By different machine, I mean the same code deployed to different servers and then being browsed to from the same browser.