0x800A03EC exception on Excel.ApplicationClass.Save

Question

I am able to populate Excel spreadsheet in my C# Windows app. However, when the program attemps to save the Excel application to a file, I get a Windows SaveAs dialog box. If I cancel out of that dialog box I get the 0x800A03EC error. I want to save the file without popping the dialog box. Please advise. The code is as follows. -------------- Excel.Application excel= new Excel.Application(); int rowIndex=1; int colIndex=0; excel.Application.Workbooks.Add(true); // Code to populate excel goes here excel.Visible=true; excel.DisplayAlerts=false; excel.Save(@"c:\fault.xls"); ---------------