for delphi code : what type of tested applications should be used.

The type of your tested application depends on technology, used by developers. The scripting language, which is used for testing, depends on your choice. You can test Java application using Python scripts, Windows application - with JScript and so on. If you don't know what technology used in your application, ask developers.

Are you getting the catastrophic error when creating the project?  Or when you run something? When does it come up?

Generally speaking, when you are creating a project and you get to that step of "Specify the type of application under test", it doesn't lock the project into anything particular... it simply sets up the default template of what will be included in the project.  For example, if you're doing a web application, it will automatically add to the project certain Web Testing components.  But really, ANYTHING can be added to a project at any time.  As the help indicates, if you're not sure, use "Generic Windows Application" and then you can adjust as need be...

So... back to my original question: When are you getting the catastrophic error?