Sub nb_instances()
Dim strComputer As String, WMIService As Object, TaBlExcel As Object
strComputer = "."
Set WMIService = GetObject("winmgmts:" & "{impersonationLevel=impersonate}!\\" & strComputer & "\root\cimv2")
Set TaBlExcel = WMIService.execquery("select * from win32_process where name='EXCEL.EXE'")
Debug.Print "Nombre d'instances : " & TaBlExcel.Count
Set WMIService = Nothing
Set TaBlExcel = Nothing
End Sub