Try this sort of thing all throughout your project:
VB Code:
  1. Dim objXLApp as Excel.Application
  2. Set objXLApp = new Excel.Application
  3.  
  4. If not (objXLApp is nothing) then
  5.     ' Object's created fine - run code against it here
  6.  
  7.     objXLApp.workbooks(1).close
  8.     objXLApp.Quit
  9.     Set objXLApp = nothing
  10. End If

By doing this, you avoid errors when you check the objects are open/created before you use them, and you release them from memory shen they are no longer needed (most objects will have some kind of close() or exit() etc. method you can call & you should always use the "Set xyz = nothing" call when you're finished with an object)...