"Attempted to read or write protected memory" while opening word document

Hi,
I have a small c# application that opens a word document and get all the content from it, then loads it in the clipboard. It works perfectly on my development machine, however, when I move it to the end-user computer at my job, this message shows up:

Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

Stack trace:
System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
at Microsoft.Office.Interop.Word.Documents.Open(..)

Below is my code. At first I thought it would be document's permission, however, I have full permission to both documents and it's in the root of my C drive.

I doubt it is related to my word version... I use Microsoft Word 11.0 Object Library, and I have word 2003 on my development machine, while word 2002 is on the end-user machine..

I included all the required dll in my application's main directory, no change. The same framework is on both machine.

Any idea on what's going on?

Object PhonebookDirectory = @"C:\mydoc.doc";
Word.ApplicationClass wordApp = new Word.ApplicationClass();
Word.Document mDoc = wordApp.Documents.Open(ref PhonebookDirectory, ref nullobj, ref nullobj, ref nullobj, ref nullobj, ref nullobj, ref nullobj, ref nullobj, ref nullobj, ref nullobj, ref nullobj, ref nullobj, ref nullobj, ref nullobj, ref nullobj, ref nullobj);
mDoc.ActiveWindow.Selection.WholeStory();
mDoc.ActiveWindow.Selection.Copy();
 
IDataObject data = Clipboard.GetDataObject();
String sCache = data.GetData(DataFormats.Text).ToString();

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