All client computers were unable to register to the remote Task Server.

Even task agent on task server was unable to register to itself.

Most of the clients were registering to SMP installed Task Server & affecting its performance.

Runtime Error displayed while using IE.

Priority: 2
Date: 12/06/2012 4:24:03 PM
Tick Count: 472642375
Host Name: TaskServer
Process: AeXNSAgent.exe (3940)
Thread ID: 5416
Module: AeXNetComms.dll
Source: AeXNetworkTransport
Description: Get 'http://TaskServer.example.com/Altiris/ClientTaskServer/GetComputerCount.aspx' failed: Invalid data received in HTTP response. Expected 3888 bytes, received 0 (-2147024883)

Priority: 2
Date: 12/06/2012 4:24:03 PM
Tick Count: 472642375
Host Name: TaskServer
Process: AeXNSAgent.exe (3940)
Thread ID: 5416
Module: AeXNetComms.dll
Source: CoNetworkTransport(144)
Description: Invalid data received in HTTP response. Expected 3888 bytes, received 0 (-2147024883)

ITMS 7.1 SP2 MP1, MP1.1,

Win2003, Win2008 Task Server

Corrupt/misconfigured version .net installed on server

Using the following link gives error. Normally it should return a count of computers registered.

'http://task server.example.com/Altiris/ClientTaskServer/GetComputerCount.aspx'

Please review the following steps to resolve this issue.

1. Please restart all altiris services on Task Server.
a) Altiris Client Task Data Loader
b) Altiris Object Host Service
 

2. Please make sure all Task Server ports are binding
ports 50121 & 50124
Run netstat -an | more to verify if the ports are binding.

For details review the following KB.
Title: Task server on SMP unable to bind on ports 50121 and 50124 
KB   https://knowledge.broadcom.com/external/article/156347

3. If Task Server is listening on the port but still unable to register to itself & other clients are unable to register
a) review Task Server logs

4. the security on the ClientTaskServer virtual directory in the IIS.
Besides the anonymous access being enabled, The Integrated Windows authentication should be enabled and basic authentication selected.

5. IIS running on Windows Server 2003 uses the NETWORK SERVICE account as the default account for the Default Application Pool. Using Windows Explorer, confirm that the NETWORK SERVICE account has Read & Execute, List, and Read NTFS permissions to the root directory where Task Server is installed. For example if Task Server is installed to "E:\Program Files\Altiris\Client Task Server," begin checking the permissions at E:\.

6. re-registering ASP.NET 2.0
Try the the command line below run on the TS:
C:\Windows\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe -i
 

7. After registering .net and  restarting IIS & all Altiris services, if TS is not able to register to itself, then
a) Simply uninstall .net 2.0 & 3.5.
b) reinstall .net 2.0 & 3.5. with correct Service Pack.
c) repair TS installation.

8.  Restart SMP client agent.
review port binding i.e. Step 2.
Task Server should be able to register to itself & all other clients should start registering to this Task Server

9. Check where is the Agent installed and if the "Altiris" root folder has the correct permissions
We observed in some environments that the whole Altiris Agent installation was on another drive and the "Altiris" root folder didn't have the proper permissions.
http://TaskServer.example.com/Altiris/ClientTaskServer/GetComputerCount.aspx usually reports Error 500, Internal server error.

To solve this issue, please add to the whole folder "Authenticated Users" read and execute permissions.
After that, if possible, restart the site server or restart IIS, "Symantec Management Agent", "Altiris Client Task Data Loader" and "Altiris Object Host Service" services.
Check again http://TaskServer.example.com/Altiris/ClientTaskServer/GetComputerCount.aspx and it should return now the correct count of computers registered.

Related KBs:

KNOWN ISSUE: Task Server's Object Host Service fails to bind on all ports 
https://knowledge.broadcom.com/external/article/177080/known-issue-task-servers-object-host-ser.html

Title: Task clients unable to communicate with Notification Server (SMP). Ports 50121 and 50124 not binding. 
https://knowledge.broadcom.com/external/article/154821/task-clients-unable-to-communicate-with.html