How can I remove .NET 3.5 SP1 and / or .NET 2.0 SP2 and reinstall .NET 3.5?

Please first make a complete backup of the Notification Server before proceeding with the below steps.
If you have only installed .NET 3.5 and .NET 2.0 SP2, use the following steps:

1. Uninstall .NET 2.0 SP2 from Add or Remove Programs

If you have installed .NET 3.5 SP1 (which includes .NET 2.0 SP2 and .NET 3.0 SP2), use the following steps:

1. Uninstall .NET 3.5 SP1 from Add or Remove Programs
2. Uninstall .NET 3.0 SP2
3. Uninstall .NET 2.0 SP2
4. Reinstall .NET 3.5

After you have reinstalled .NET 3.5 (which includes .NET 2.0 SP1 and .NET 3.0 SP1) please make sure that the Default Web Site in IIS is set to use .NET 2.0.

After the re-installation IIS will prohibit .NET 2.0 usage by default and will result in the following errors:

Log File Name: a.log
Priority: 2
Date: 4/7/2009 11:52:19 AM
Tick Count: 1868671
Host Name: *********
Process: AtrsHost (1528)
Thread ID: 4
Module: AtrsHost.exe
Source: Altiris.TaskManagement.ClientTask.*
Description: System.Net.WebException: The remote server returned an error: (404) Not Found.
   at System.Net.HttpWebRequest.GetResponse()
   at Altiris.ClientTask.Server.ClientTaskServer.RegisterTaskServer(TaskServerGroupGuid serverGuid, Guid serverSecret)

Log File Name: Agent.log
Priority: 1
Date: 4/7/2009 4:30:02 PM
Tick Count: 6996453
Host Name: ********
Process: aexnsagent.exe (1152)
Thread ID: 1180
Module: aexnsagent.exe
Source: ConfigServer
Description: RequestPolicies failed: HTTP error: 404 Not Found (-2147209951)

Allow .NET 2.0 usage in the IIS Web Extensions and reload the console.