[jQuery] Ajax request not working in IE7. Works in IE8,FF3+

jQuery v1.3.2

I have an ajax calendar that loads when the page loads. To change the
month I use ajax to update the month view. On each ajax load I replace
the calendar container with:

... Calendar code here ...

$calHTML .= '<script type="text/javascript">

function call_cal(cal_link){

$.ajax({
type: "POST",
cache: false,
url: "'.THEME_URL.'ajax/calendar.php",
data: cal_link,
success: function(html){
$("#calendar").html(html);
}
});

}

$("#prev_month").click(function () {
var get_cal = $(this).attr("href");
var cal_link = get_cal.substring(1, get_cal.length);
call_cal(cal_link)
return false;
});

$("#next_month").click(function () {
var get_cal = $(this).attr("href");
var cal_link = get_cal.substring(1, get_cal.length);
call_cal(cal_link)
return false;
});

</script>';

In IE 7 the prev_month and next_month buttons stop working after the
second click. Any ideas?