The following steps describe how to completely uninstall and reinstall the package server, and the underlying Symantec Management Agent (agent), and then reinstall them.
You may want to do this if the package server is not functioning as desired.

1. On the Site Server, save the folders in the package delivery folder, by default the folder is:
     C:\Program Files\Altiris\Altiris Agent\Package Delivery

2. On the Site Server, delete the package.xml files from each subdirectory in the Package Delivery folder in the back up just taken.

  Note:  If the SMP version is 7.5x the files to delete will be snapshot.xml and snapdata.xml

3. From the console, remove the site server components from the site server.
    Settings > Notification Server > Site Server Settings,
    Site Management > Site Servers > (server of interest) > Services,
    Click: Install/remove services
    Uncheck all services

4. From the console, run a delta membership update
   Settings > Notification Server > Resource Membership Update,
   In the Delta Membership section, click Run
   wait for confirmation the update completed

5.a. From the site server, uninstall the Altiris agent
    cd "C:\Program Files\Altiris\Altiris Agent\"
    AeXAgentUtil.exe /stop
    AeXNSAgent.exe /uninstall

See:
   What is the best way to cleanly uninstall the Symantec Management Agent to leave no remnants (or the bare minimum) behind?
   http://www.symantec.com/docs/HOWTO45738

5.b. From the console, delete the computer resource
    Manage > Computers
    All Computer Views > All Computers
    right-click on computer, select delete

6. From the console, reinstall the core agent
   Settings > Agents/plugins > Symantec Management Agent,
   Symantec Management Agent > Settings > Symantec Management Agent Install
   in Rollout Agent to Computers section
   add name of the site server
   Click "Install"
   Adjust Symantec Management Agent Installation Options, as appropriate.
   Watch SMA to install

7.a.  From the console, start process to reinstall site server components to the site server.
    Settings > Notification Server > Site Server Settings
    Add > Site Server
    select the site server
    select site server components of interest

7.b.  From the console, run a delta membership update (see above)

7.c.  From the site server, update configuration; confirm that package service installs. If the package server does not install, see notes below.


8. Copy the Package Delivery folder from step 1 to the proper installation directory, while the Altiris agent is stopped.
    cd "C:\Program Files\Altiris\Altiris Agent\"
    AeXAgentUtil.exe /stop
    ...
    AeXAgentUtil.exe /start


At this point the package server agent should be installed and synchronizing the packages with the NS. The rest of the plug-ins should install once the package server agent finishes its automated procedures.
Allow the NS to run it's normal scheduled tasks overnight.


Notes:

To confirm the location of the package delivery folder on the PS, run the following commands. They should all yield the same result.
   reg query "HKLM\SOFTWARE\Altiris\Altiris Agent\Plugin Objects\Agents\Package Server" /v "Install Path"
   reg query "HKLM\SOFTWARE\Altiris\Altiris Agent\Package Server" /v "PackageServerBaseDir"

   net share
   net share PkgSvrHostC$

To manually install the package server agent run the AeXNSCPkgSvr.exe /install, from either:
    \\ns-server\NSCap\bin\Win32\X86\PkgSvr Agent Package\
    C:Program Files\Altiris\Notification Server\NSCap\bin\Win32\X86\PkgSvr Agent Package\