i am also facing the same problem
actually i dont have problem if the user of the system will be end up with all the application stopped when i dispose my excel object
i just want to dispose my application's excel object.
one more thing i would like to mention
when i write something like
if (objExcel != null)
objExcel.Visible = false;
objExcel = null;
the red line will ask me that "do u want to save the excel sheet or not "
and if i press Cancel button it gives that HRESULT error