I have a chart inside a panel. If I use this config for the panel, collapsed: false everything works fine. The problem occurs if I use collapsed: true. When I click to expand the panel it takes about 1 minute to render the graph, and often I get an uncatch error. This problem occurs in IE8 not in FF. Since 100% of my users are on IE I got to fix this. I would like to load the application with all the chart panel collapsed.

Thanks in advance for helping me.

In more details
I have a tabPanel with an item defined like this
Code:
title: 'Indicateurs',
           bodyStyle: 'padding:10px;',
           autoScroll:true,
           contentEl: 'graphcontainer'
I create several panels in this TAB using this:
Code:
new Ext.Panel({
  renderTo: 'graphcontainer',
autoWidth: true,
        height: 450,
  monitorResize: true,
        title: 'Transports ambulanciers, hospitalisations et temprature, RSS ' + rss,
  frame:true,
   layout:'fit',
  collapsible: true,
  collapsed: true,
  titleCollapse: true,
  animCollapse:false,
  id: 'chartPanel3',
        items: 
  {
          xtype: 'columnchart', 
    url:Ext.chart.Chart.CHART_URL,
          store: store1,
          series: seriesDef,
          xField: "datereleve",
          yAxes: axes,
          chartStyle: styleDef
        }
    });//fin du ext.panel