Word Interop Application casting error in Vista   

I have a Windows app that uses the Primary Interop Assemblies for Word.  It 
runs just fine on XP machines.  It does not on Vista.  The Vista machine is 
running Word 2003, so I installed the O2003PIA assemblies.  However, I get 
the following error when trying to access Word:

Unable to cast COM object of type 
‘Microsoft.Office.Interop.Word.ApplicationClass’ to interface type 
‘Microsoft.Office.Interop.Word._Application’.  This operation failed because 
the QueryInterface call on the COM component for the interface with IID 
‘{00020970-0000-0000-C0000-000000000046}’ failed due to the following error: 
No such interface supported (Exception from HRESULT: 0x80004002 
(E_NOINTERFACE)).


I am defining my word application object like this:
 Word.Application _wordApp = new Word.Application();

I've also tried:
 Word._Application _wordApp = new Word.Application();  //can't instantiate a 
_Application object)

Both give me the same error.

Is there something special I have to do for Vista?

Bonnie

date: Mon, 3 Dec 2007 07:25:01 -0800   author:   EruditeBonnie