.Net Error Message: .Net 3.0 & 3.5 installation errors

Error Message:

[11/21/07,08:52:42] Microsoft .NET Framework 3.0a: [2] Error: Installation failed for component Microsoft .NET Framework 3.0a. MSI returned error code 1603
[11/21/07,08:55:36] Microsoft .NET Framework 3.0a: [2] Error: Installation failed for component Microsoft .NET Framework 3.0a. MSI returned error code 1603
[11/21/07,09:10:30] Microsoft .NET Framework 3.0a: [2] Error: Installation failed for component Microsoft .NET Framework 3.0a. MSI returned error code 1603
[11/21/07,09:10:36] WapUI: [2] DepCheck indicates Microsoft .NET Framework 3.0a is not installed.
[11/21/07,09:12:06] Microsoft .NET Framework 3.0a: [2] Error: Installation failed for component Microsoft .NET Framework 3.0a. MSI returned error code 1603
[11/21/07,09:12:11] WapUI: [2] DepCheck indicates Microsoft .NET Framework 3.0a is not installed.
[11/21/07,09:25:28] Microsoft .NET Framework 3.0a: [2] Error: Installation failed for component Microsoft .NET Framework 3.0a. MSI returned error code 1603
[11/21/07,09:25:32] WapUI: [2] DepCheck indicates Microsoft .NET Framework 3.0a is not installed.
[11/21/07,09:38:12] Microsoft .NET Framework 3.0a: [2] Error: Installation failed for component Microsoft .NET Framework 3.0a. MSI returned error code 1603
[11/21/07,09:38:17] WapUI: [2] DepCheck indicates Microsoft .NET Framework 3.0a is not installed.
[11/21/07,09:43:32] Microsoft .NET Framework 3.0a: [2] Error: Installation failed for component Microsoft .NET Framework 3.0a. MSI returned error code 1603
[11/21/07,09:56:03] Microsoft .NET Framework 3.0a: [2] Error: Installation failed for component Microsoft .NET Framework 3.0a. MSI returned error code 1603
[11/21/07,09:56:08] WapUI: [2] DepCheck indicates Microsoft .NET Framework 3.0a is not installed.
[11/21/07,10:15:10] Microsoft .NET Framework 3.0a: [2] Error: Installation failed for component Microsoft .NET Framework 3.0a. MSI returned error code 1603
[11/21/07,10:38:23] Microsoft .NET Framework 3.0a: [2] Error: Installation failed for component Microsoft .NET Framework 3.0a. MSI returned error code 1603
[11/21/07,10:38:28] WapUI: [2] DepCheck indicates Microsoft .NET Framework 3.0a is not installed.

Solution:

First - 1

Stop the World Wide Web service.
Open IIS and try to stop it from there, or goto My Computer. Right Click. Manage Services.
Then close service named World Wide Web Publishing.

Second- 2

1. Uninstall IIS service and related components.
2. Reinstall IIS server and asp.net etc.
3. Install .Net 3.5 .