[jQuery] Using back button causes C.easing[e.easing || (C.easing.swing ? "swing" : "linear")] is not a function

[Frank Peterson]

I am doing some ajax and calling a function every 5 seconds and it
works perfect except when I press the back button and then gives this
error on the next ajax load

C.easing[e.easing || (C.easing.swing ? "swing" : "linear")] is not a
function



HERE IS MY CODE
$(document).ready(function()
{
        timer_set = 0;
        prevnext();
});

function prevnext()
{
        //optional arguments, create the extra query string
        var next_param = (arguments[0]) ? '&next=' + arguments[0] :
'&next=1';
        var numsent_param = (arguments[1]) ? '&numsent=' + arguments[1] : '';
        var extraparameters = next_param + numsent_param;

        $.ajaxSetup({timeout: 5000});
        $.ajax({
                type: 'POST',
                url: 'http://example.com/request.php',
                data: 'url=' + encodeURI('http://example.com/data.xml') +
'&maxlength=' + encodeURI('3') + extraparameters,
                beforeSend: function() {
                        if (timer_set)
                                clearTimeout(video_ajax_timer_id);
                        $('#video_ajax_gallery').empty();
                        $('#video_ajax_gallery').append('<div 
id="ajax_loading">loading</
div>');
                },
                error: function(){
                        $('#video_ajax_gallery').append('Error loading data.');
                },
                success: function(msg){
                        $('#video_ajax_gallery').append('<div
id="video_gallery_container"></div>');
                        $('#video_gallery_container').append(msg);
                        $('#video_gallery_container').fadeOut(1,function(){
                                $('#ajax_loading').hide();
                        });
                        $('#video_gallery_container').fadeIn('slow', function(){
                                video_ajax_timer_id = setTimeout("prevnext(1, 
next_video_num)",
5000);//next_video_num is set in response
                                timer_set = 1;
                        });
                }
        });
}