Hi All,
I am automating excel using C#. I have created a .Net Class library which launches excel, and hooks to some of its events, and connects to an excel COM addin.
There are 2 scenarios in which excel is launched:
1. Excel is launched(through the above DLL), and an existing workbook is opened WITHOUT ANY USER INTERACTION. User performs some operations on the workbook, and closes excel. Excel is released by the launcher dll from the memory.
2. Excel is launched(through the above DLL), and excel File..Open fialog is presented to user. User selects the file to load in excel and loads it. User performs some operations on the workbook, and closes excel. Excel is released by the launcher dll from the memory.

Now, in scenario #1, the excel process is terminated properly from the memory and is automatically removed from the Task Manager. But in case of Scenarion #2, the excel process still remains in memory, though the same cleanup code runs to release excel. The only difference between the two operations is the introduction of the File...Open dialog code. The FileDialog object is released immidiately after its usage.

Here is how I open workbook in excel in Scenario #1:
              m_Workbook = m_ExcelApp.Workbooks.Open(docName, Missing.Value, false, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, true, Missing.Value, Missing.Value, true, Missing.Value, Missing.Value);

Here is how I open workbook in excel in Scenario #2:
               Microsoft.Office.Core.FileDialog fdlg = m_ExcelApp.Application.get_FileDialog(Microsoft.Office.Core.MsoFileDialogType.msoFileDialogOpen);
               
               fdlg.AllowMultiSelect = false;

               if (fdlg.Show() != 0)
               {
                   if (fdlg.SelectedItems.Item(1) != string.Empty)
                   {
                       
                       m_Workbook = m_ExcelApp.Workbooks.Open(fdlg.SelectedItems.Item(1), Missing.Value, false, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, true, Missing.Value, Missing.Value, true, Missing.Value, Missing.Value);
     }
 }
 //clean up file dialog
               System.Runtime.InteropServices.Marshal.ReleaseComObject(fdlg);
               fdlg = null;
               GC.Collect(); //Force Garbage collection after clean up. (See KBID - 317109)
               //end clean up

Here is the common cleanup code after user closes Excel:

               System.Runtime.InteropServices.Marshal.ReleaseComObject(m_Workbook); //release workbook
               System.Runtime.InteropServices.Marshal.ReleaseComObject(m_ExcelAddinApp); //release addin object
               System.Runtime.InteropServices.Marshal.ReleaseComObject(m_ExcelApp); //release excel application object

               m_Workbook = null;
               m_ExcelAddinApp = null;
               m_Workbook = null;

               //Force Garbage Collection after cleanup. (See KBID - 317109)
               GC.Collect();

Is there anything that I am missing out here?
Any quick help will be highly appreciated, since I am already on a tight schedule.

Thanks,
Sarang