>Then later on I changed the DLL classes from a Visual Class
>Libraries to PRG's, so I could take advantage of _COMARRAY
>and HELPString.
>
>Now when I run the setup, I get an error:
>
>"Error 1911. Could not register type library for file
>c:\mydll.dll. Contact your support personnel"

Long shot: did you choose "Regenerate Component IDs"? If not, something might be confused because you changed the COM contract by adding the COMARRAY and HELPSTRING material.