Invalid worksheet name while exporting datagrid to excel in asp.net

Hi, I am having trouble renaming the excel sheet while exporting to excel. we have a datagrid that contains some analytical data. I have the name to the excel file as "temp.xls" inside the code. When the user clicks on the Export to Excel button next to datagrid, it opens a popup with options Open, Save and Cancel. When I click open, it opens the excel sheet with the sheet name as .xls[temp[1] and the excel filename as temp[1].xls. As a result when the user selects the data and try to use pivot table with that data it is giving an error. I am thinking if I change the sheetname, then the pivot table would work. Please let me know. My code is as follows HttpContext.Current.Response.Clear(); HttpContext.Current.Response.Charset = ""; HttpContext.Current.Response.ContentType = "application/vnd.ms-excel"; //With Ref to the Bug 01219DRY HttpContext.Current.Response.AddHeader("Content-Disposition", "Attachment;filename=InvDetails.xls"); str ...