When selecting the link "Show me this page" in the Symantec Management Agent Install page, or even when manually attempting to open the page http://localhost/Altiris/NS/Agent/AltirisAgentDownload.aspx an HTTP 404 error is thrown:
HTTP Error 404.0 - Not Found
The resource you are looking for has been removed, had its name changed, or is temporarily unavailable.
The Altiris Service had somehow been changed to start with the logon account of Local System. The correct logon account should be the Altiris or Application Identity account used when the platform was installed (or a local or domain account with rights to the Symantec_CMDB database)
Changed the service logon to the correct account and restarted the services.
Symantec Management Platform 7.1 SP2