I have a web app using vb/aspx and using a com object.

In one place in the code, using one of the classes in the object, the version on the prod box returns "QueryInterface for interface myobject.thisoneparticularclass failed." The same code works fine on my test box. I read up a bit on the QueryInterface, but don't know why it is failing.

The two boxes have the same operating system/service pack, and the same myobject.dll com object. Is there an inconsistency in the interop between the two servers? How do I check? What else could it be?

Thanks