The cause of this particular problem with Ibrahim was that MSI was not working on the machines showing this error. Re-registering MSIEXEC resolved the problem.
From a commandline run MSIEXEC /REGSERVER
I have tried the solution linked in the OP and I have verified that I re-registered MSI.
When I try to distribute the WSUS certificate via the Server Publishing Wizard the Eminentware server fails with the same as mentioned above:
The results of the distribution of the signing certificate:
SERVER NAME Status: Failure Message: InvalidNamespace Invalid namespace
Solved. I disabled UAC on both the WSUS and EminentWare server and its now working.
Disabling UAC is one available option.
When the WSUS and ExtPack server are installed on the same machine, the other option is to configure the local Administrator account as the credential to use for WMI connections.
If the WSUS and ExtPack server are installed on separate machines, typically this is caused because the WMI Providers cannot be installed onto the ExtPack server. If the ExtPack is installed on Windows Server 2008, or R2, this is almost always because File & Print Sharing has not been enabled in the Network Sharing Center and/or the WMI Ruleset has not been enabled in the Windows Firewall (if the WF is enabled).
You can work around the F&PS limitation by executing the WMI Provider installer on the ExtPack server, which can be found in the ExtPack installation folder in ~\EminentWare\packages\EminentWare; however, if the Windows Firewall is enabled, the WMI ruleset must be explicitly enabled.