Re: NeatHTML Error
The error you saw when you tried to open the file in VS is just VS being stupid. You should ignore it. If you want to open the xsd files you'll probably have better luck with Notepad. For now, to avoid getting misleading results from future tests, please restore the xsd files to their original state (e.g. by copying over them with the ones from the zip archive).
My best guess at the moment is that there might be something a little odd about your installation. What version of the .NET Framework is mojoPortal running under? Since you are using VS2003, I'm guessing it is 1.1, but I'm curious what the full version is. If you recreate the original error, the full version number of the .NET Framework should be at the bottom of the error page. Any chance you are running an old version of .NET 1.1 or some beta version .NET 2.0?