Installation failed for component Windows Workflow Foundation for .NET 3.0 RC1

I am attempting to install .NET 3.0 RC 1 and have run into the following error;

09/26/06,07:41:26] Windows Workflow Foundation: [2] Error: Installation failed for component Windows Workflow Foundation. MSI returned error code 1603
[09/26/06,07:42:15] WapUI: [2] DepCheck indicates Windows Workflow Foundation is not installed.
[09/26/06,07:42:16] WapUI: [2] DepCheck indicates Microsoft .NET Framework 3.0 was not attempted to be installed.

I have removed all previous CTP's and components use Add and Remove programs and run the remove tool which reported that there was nothing to remove.

Anybody have an idea what I have missed here?

[670 byte] By [Kendrew] at [2007-12-24]