I found this misfunctionality accessing to the OOo through OLE Automation Bridge
for manipulating the toolbars. According to the API defined for a
XIndexContainer implementation object, this method expects for 2 parameters: Any
Object and the index where the first one must be inserted (in the underlaying
data structure). The problem appears when for adding a item to a toolbar is
needed to use this method, passing it a com.sun.star.lang.PropertyValue array as
parameter (where it is defined the properties of a new toolbar item). Despite of
following the instructions described on the Developers Guide about how to
construct OOo specific objects and arrays for being used thrugh OLE Automation
Bridge, the problem appears when this method was called.
-ERROR REPRODUCTION-
Environment: Windows XP (SP1), OOo Beta 2, a minimal VB.NET application(*)
(*)
Private Sub createToolbarB_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles createToolbarB.Click
       Dim objSM As Object = CreateObject("com.sun.star.ServiceManager")
       Dim CoreRef As Object =
objSM.CreateInstance("com.sun.star.reflection.CoreReflection")
       Dim classPV As Object = CoreRef.forName("com.sun.star.beans.PropertyValue")
       Dim aToolbarItemProp1 As Object
       classPV.CreateObject(aToolbarItemProp1)
       Dim aToolbarItemProp2 As Object
       classPV.CreateObject(aToolbarItemProp2)
       Dim aToolbarItemProp3 As Object
       classPV.CreateObject(aToolbarItemProp3)
       Dim properties As System.Array
       properties = System.Array.CreateInstance(aToolbarItemProp1.GetType, 3)


       aToolbarItemProp1.Name = "CommandURL"
       aToolbarItemProp1.Value = "macro:///standard.module1.TestIt"
       aToolbarItemProp2.Name = "Label"
       aToolbarItemProp2.Value = "Test"
       aToolbarItemProp3.Name = "Type"
       aToolbarItemProp3.Value = 0

       properties(0) = aToolbarItemProp1
       properties(1) = aToolbarItemProp2
       properties(2) = aToolbarItemProp3

       Dim Doc As Object
       Dim dummy As System.Array
       Dim objDummy As Object = New Object()
       dummy = System.Array.CreateInstance(objDummy.GetType, 0)
       Doc =
objSM.createInstance("com.sun.star.frame.Desktop").loadComponentFromURL("private:factory/swriter",
"_blank", 2, dummy)
       Dim LayoutManager As Object = Doc.currentController.Frame.LayoutManager
       LayoutManager.createElement("private:resource/toolbar/user_toolbar1")
       LayoutManager.showElement("private:resource/toolbar/user_toolbar1")
       Dim ToolBar As Object =
LayoutManager.getElement("private:resource/toolbar/user_toolbar1")
       Dim settings As Object = ToolBar.getSettings(True)
       settings.insertByIndex(0, properties) '<== ERROR IS THROWN IN THIS LINE
       ToolBar.setSettings(settings)
   End Sub

The message error shown by application is following:
"com.sun.star.lang.IllegalArgumentException: Type must be
com::sun::star::uno::Sequence< com::sun::star::beans::PropertyValue >"