I'm not sure if this will help you, maybe you're already doing this, but this is the script I use to create an excel file and save my results.
See this link -
http://support.microsoft.com/kb/234774 //Start Excel and get Application object.
var oXL = new ActiveXObject("Excel.Application");
oXL.Visible = true;
//Get a new workbook.
var oWB = oXL.Workbooks.Add();
var oSheet = oWB.ActiveSheet;
//Save values to a cell
oSheet.Cells(1, 1).Value = "Something";
//Save excel file and close
oWB.SaveAs("C:\MyExcel.xlsx");
oXL.Quit();