Trouble running sample portal application

I just installed 9.2 and was going through the tutorial to set up the sample
portal application. (on Windows 2000)

When I try to start the server, I get an error "Module named 'MyPortalEar'
failed to deploy".

The details says:

weblogic.application.ModuleException: Exception preparing module:
EJBModule(wps.jar: Unable to deploy EJB:MailService from wps.jar. The run-as
security principal 'portaladmin' chosen for the EJB
'MailService'(Application: myPortalEar, EJBComponent: wps.jar)' is not a valid
user principal in the current security realm. Please specify a valid user for
the EJB to use.

Now, given that am running the OOTB example, I don't expect to have to create a
portaladmin user.

Any ideas?

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