These two problems are characterized by the user being unable to succesfully input their product code into "Simple License Entry" box. It can appear as one of two possible errors...
Both of these errors are caused because something is interferring with your ability to contact our licensing servers. This could be because of an anti-virus, admin permissions, firewall, or network issue. The guide linked below will walk you through the process of generating a license file manually and installing PTC Creo 2.0 without using the "Simple License Entry".
It seems like the links to generate a license file are not working anymore, any other ways to fix this problem?