Session problem with firefox

i am facing a critical problem accessing the session variable.
Actually i call aspx page using ajax . The calling page set the session variable with value. After ajax process is completed and i want access session value from other aspx page.
Then Error message shows
say default2.aspx:-

Response.Write(Session[“USID”].ToString());
Object reference not set to an instance of an object.

default.aspx (call by ajax)
Session[“USID”] = “matrix”;

Above problem is raising only firefox browser

please need your suggestion how can i overcome above problem

Since the problem only occurs in firefox, try adding the following script between the head tags in the html of the page:

<script type=“text/javascript”>
var IsIE = false;
var IsLessIE7 = false;

</script>

<!–[if IE]>
<script type=“text/javascript”>
IsIE = true;
</script>
<![endif]–>

<!–[if LT IE 7]>
<script type=“text/javascript”>
IsLessIE7 = true;
</script>
<![endif]–>