C# VS2005 / Word Automation / Documents.Open closes open document

[RKovach]

I am automating Word and getting the existing instance if available using the following:

Word.Application oWord = null;        
Word.Document oDoc = null;
object oMissing = System.Reflection.Missing.Value;    
object sFN = @"C:\Test\TestDoc.doc";
 
try 
{
     // Is Word running? 
     oWord = Marshal.GetActiveObject("Word.Application") as Word.Application; 
}
catch (COMException ce)
{
     if (ce.ErrorCode == unchecked((int)0x800401E3))
       // No, Word not in ROT, start a new instance 
       oWord = new Word.Application();
}

And that is working just fine, and then I am opening a document with:

oDoc = oWord.Documents.Open(ref sFN,ref oMissing,ref oMissing,ref oMissing,ref oMissing,ref oMissing,
    ref oMissing,ref oMissing,ref oMissing,ref oMissing,ref oMissing,ref oMissing,
    ref oMissing,ref oMissing,ref oMissing,ref oMissing);

However, if I have a Word document already open when I do that my Open statement is replacing the open document with the one I am loading.

I have searched high and low and cannot find any reference to this behavior.

Anyone ever encountered this?

Thanks in advance...RK