How do I call a COM object?

I have a COM interop object (NOT MS OFFICE  objects)  that I am trying to use in my ASP.NET application.  The ONLY way I can get it to work is if the COM (via DCOM) identity is set to "The Interactive User" and I am physically logged into the web server (Windows 2008 Ent).
If I log off (or disconnect the session), I get the 0x8000401a (configured identity is incorrect).  
I have tried setting the app pool identity user to "This User" and get the 0x80080005 (CO_E_SERVER_EXEC_FAILURE) error (I get the same error if the identity is set to "the launching user").
How do I get this thing to work?
TIA!
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