QueryInterface for interface Word._Application failed

[Delphi]

Hi

private Word.ApplicationClass wApplication=null;
private Word.Document wDoccument=null;
wApplication =new Word.ApplicationClass();
object objNewTemplate=System.Reflection.Missing.Value;
object objDocType=System.Reflection.Missing.Value;
object objIsvisible=false;

wDoccument=wApplication.Documents.Add (ref objWordTemplateName,ref
objNewTemplate, ref objMissing,ref objIsvisible );

I am using word introp in C# dotnet.
On Execution of of document.add() line of above code i am getting an
exception "QueryInterface for interface Word._Application failed". Here i am
providing objWordTemplateName as path to a template. I am using word introp
9.0 in my application. In debug mode if i put break point in above same line
i am getting Exception "System.ExecutionEngineException not found". But if i
put break point in the catch statement of the above code i am getting the
exception.message "QueryInterface for interface Word._Application failed" .
In some computer this code is working but some system this code giving
exception. All of our computer works on windows Xp with sp2

Thank you
Delphi