My error: The MOF compiler could not connect with the WMI server. This is either because of a semantic error such as an incompatibility with the existing WMI repository or an actual error such as the failure of the WMI server to start.
Use Windows Install Clean UP (don't do this if you have databases you need to retrieve unless you back them etc.)
Remove all the SQL 2008 installations.
Go back to the installer and ONLY install the SQL instance (not analysis services, not reporting)
Also, use NT Authority/Network Services to install for permissions (just keep this simple - don't add any other user except the local admin and install under the local admin account)
Once you get the MSSQLServer installed, you can go back and reinstall and configure your users and settings, but I did not find any other way around the MOF compiler problem.