You need to set up the Refering URL for both ABC.com and XYZ.com so that you don't see the errors when you try to login. That's in your Control Panel -> General Settings section.
Also - make sure that everyone has got the browser setup correctly so that they can accept cookies from even a framed site. There is more detail here
Browser ProblemsPlease let me know if that helps.
Regards,
Brett Harris
Infopop Corporation
[This message was edited by Brett Harris on December 17, 2002 at 09:48 AM.]