Error Install Platform Unsupported 1633 on .NET Framework 1.1 Installation

ERROR_INSTALL_PLATFORM_UNSUPPORTED 1633 This installation package is not supported on this platform. Contact your application vendor.

I am installing the .Net framework 1.1 on Windows 2000 SP4, running an AMD Athlon 2800+. It drops out with a vague error message "cannot be installed on this platform". I checked the dotNetfx.log and came up with this:

[04/29/04,17:24:23] Starting Install.exe

[04/29/04,17:24:23] Parsing switches from commandline: C:DOCUME~1ADMINI~1LOCALS~1TempIXP000.TMPInstall.exe

[04/29/04,17:24:23] SourceDir: C:DOCUME~1ADMINI~1LOCALS~1TempIXP000.TMP[04/29/04,17:24:23] Install started

[04/29/04,17:24:23] Checking system requirements

[04/29/04,17:24:23] OS: Win 3.1

[04/29/04,17:24:23] Ver:

[04/29/04,17:24:23] SP: ò

[04/29/04,17:24:23] Preparing Dialog

[04/29/04,17:24:23] Message: Microsoft .NET Framework is not supported on this platform.

[04/29/04,17:24:24] Install.exe returning 1633

[04/29/04,17:24:24]

[Install.exe]

ReturnCode=1633

Can anyone help? Please.