jQuery Grid Plugin - jqGrid

HI, i have some problems with the qgrid columnchooser in IE8.

I have three pages, each one of them has a jqgrid inside, which show some datas received from an ajax call to a php which execute an SQL (one different query for each grid).

All pages works fine with chrome and firefox, but only the first two pages work fine with IE8 too.

The only difference from the pages is the called php, that have his own particular sql query and output.

The version of jqgrid (4.3.3) is the same in all of them.

I have tried with 4.5.2 version, but it didn't solved the problem. The only thing that made it work was reducing the number of extracted field, directly from sql.

i reduced them from 78 to 14, and the columnchooser worked fine.

I can solve this selecting only the fields i need, but if i could let them all would be perfect, so I ask you if you can help me.

jQuery("#list").jqGrid('navButtonAdd', '#pager', {
    caption : "",
    title : "Scegli colonne",
    onClickButton : function() {
        jQuery("#list").jqGrid('columnChooser', {
            "msel_opts" : $.ui.multiselect.defaults,
            "shrinkToFit" : true,
            "autowidth" : true,
            done : function(perm) {
                w = $(window).width();
                // alert('done ' + w);
                if (perm) {// alert(perm);
                    // "OK" button are clicked
                    this.jqGrid("remapColumns", perm, true);
                    // the grid width is probably changed co we can get new
                    // width
                    // and adjust the width of other elements on the page
                    // var gwdth = this.jqGrid("getGridParam","width");
                    // this.jqGrid("setGridWidth",gwdth);
                    this.setGridWidth(w - 30, true);
                    // NF rintraccia vincoli e nascondi colonne per vincoli
                    // alert('vincoli colonna');
                    /*
                     * if (VINCcolumn) { setVINCcol("list", VINCcolumn); }
                     */
                    $('.ui-search-input').show();
                } else {
                    // we can do some action in case of "Cancel" button
                    // clicked
                }
            }
        });
    }
});

Is it possible thas is caused from the number of fields?