Grid not working in IE7+8

in IE7 and IE8 this grid crashes. It is working in IE9 and FF4:

Problem occurs in v.2.6 build 100722:

colWidth is set to 100,100,"","" (needs to be set that way, cause we may need to add some extra columns

dhtmlxgrid.js:513

this._drsclmW [100,100,,]
ms = 388

var next=Math.max((this._drsclmW ? this._drsclmW[fcols[i]] : 0),ms)
this.cellWidthPX[fcols[i]]=next;
summ+=next;

–> next = NaN (cause Math.max("*", 388) is not working)

dhtmlxgrid.js:528

this.obj.style.width=summ+“px”;

–> this chrashes IE, cause summ is NaN

any suggestions?
thx Torsten

own Code:
mygrid = new dhtmlXGridObject(‘mygrid_container’);
mygrid.setImagePath(’/statics/images/grid/’);
mygrid.setSkin(“modern”);
mygrid.enableMultiselect(true);
mygrid.enableAutoHeight(true, this.getWindowHeight()-20, true);
mygrid.enableColSpan(true);
var headerText = text1 +",#cspan," +text2 +"," +text3;
var columnIds = “kwnr,kwnr_to,extRufNr,name”;
var colAlign = “center,center,center,center”;
var colTypes = “auer_input,ro,auer_input,auer_input”;
var colSorting = “int,str,str,str”;
var headerFilter = “#numeric_filter,#cspan,#text_filter,#text_filter”;
var columnMinWidth = “100,100,,”;
var columnInitWidth = “100,100,,”;

mygrid.setHeader(headerText);
mygrid.setColumnIds(columnIds);    
mygrid.setColumnMinWidth(columnMinWidth);
mygrid.setInitWidths(columnInitWidth);
mygrid.setColAlign(colAlign);
mygrid.setColTypes(colTypes);
mygrid.setColSorting(colSorting);
mygrid.attachHeader(headerFilter);
mygrid.auerValidation(auerValidation);
    
mygrid.attachEvent("onGridReconstructed", function(grid_obj) {
    if (sorting) {
        sorting.switchoff();
        sorting = null;
    }
});

mygrid.attachEvent("onCheck", function(rId, cInd, state){
    if ( cInd < 4)
        return true;
    var value = parseInt($('dectColIndex_'+cInd).innerHTML,10);
    state?value++:value--;
    $('dectColIndex_'+cInd).update(value);
    return true;
});

mygrid.init();

can you please provide complete demo where we can reproduce this issue? docs.dhtmlx.com/doku.php?id=othe … leted_demo