jQuery Grid Plugin - jqGrid

When i am loading the page with following grid I am getting an error in firefox error console- "this.call is not a function".

when the page is loading for first time, though the firefox error console shows the error messae page loads perfectly.

but when i use the browser back button to go to this same page it breakes.

following is the code to load the grid.

function LoadCustomerSearchGrid(){

  //debugger;
 
    jQuery("#tblCustList").jqGrid({
           url: 'Handlers/SearchCustomer.ashx',
        datatype: "json",
        //type: 'POST',
        height: "300",
        width:"900",
           colNames:['SOL Id', 'AC Id', 'Cust. Id', 'AC Name', 'AC Short Name', 'Schm.Type','Schm.Desc','Bal Amt.'],
           //colNames:['Column01'],
           colModel:[
               {name:'Column01',index:'Column01', editable:true,width:55, sortable:false} ,
               {name:'Column02',index:'Column02', editable:true,width:125, sortable:false},
               {name:'Column03',index:'Column03', editable:true,width:70, sortable:false},
               {name:'Column04',index:'Column04', editable:true, sortable:false},
               {name:'Column05',index:'Column05', editable:true,width:90, sortable:false},
               {name:'Column06',index:'Column06', editable:true,width:90, sortable:false},
               {name:'Column07',index:'Column07', editable:true,width:90, sortable:false},
               {name:'Column08',index:'Column08', editable:true,width:90,formatter:'currency',align:'right', sortable:false}
              
              
           ],
           rowNum:50,
           rowList:[10,20,30,40,50],
        autowidth: false,
        viewrecords: true,
        jsonReader:{
            root: "itemrows",
            page: "currentpage",
            total: "totalpages",
            records: "pagerecords",
            repeatitems: false
        },

          pager: jQuery('#divCustListPager'),      
          caption:"Customer Search Reasult" ,
          toolbar: [true,"bottom"],
          beforeRequest: function(){
                varStartTime= new Date().getTime();
                } ,
          loadComplete: function() {

              var varLoadTime=new Date().getTime();
              $("#t_tblCustList").css("text-align","right").html("Data received from Finacle DR server in "+(varLoadTime-varStartTime)+" miliseconds.");
              } ,
          afterInsertRow: function(rowid, aData){

                  var varCusIDCellData="<a href='CustomerGeneralDetails.aspx?CustId="+aData.Column03+"'>"+aData.Column03+"</a>";
                  jQuery("#tblCustList").setCell(rowid,'Column03',varCusIDCellData,{color:'green'});
                 
                  var varAcIDCellData="<a href='CustDetailsByACID.aspx?CustId="+aData.Column02+"'>"+aData.Column02+"</a>";
                  jQuery("#tblCustList").setCell(rowid,'Column02',varAcIDCellData,{color:'green'});
              
              
                 
                  }
         
         
    });

 
}