The release packages are already compiled so they don't need to be built in visual studio.

If you are using code behind for your custom feature then you need to compile that into a dll and put in the bin file. If you are using inline code (ie <script runat="server"...) you don't need to compile your code either.

I patched mojoPortal version 2.3.7.0 several times with updated dlls, so its possible that trying to rebuild it in VS would give warning about the version of the dlls, but the latest release version 2.3.7.5 has not been patched since its initial release and when I open the release files (as a web site) in VS and build the solution I get no errors. 2.3.7.5 was released on Dec 1 so I would have thought that is the version you have.

In any case as I said its already compiled and doesn't need to be built in VS and it should not have any runtime errors even if you are getting a build error. But using the latest package you should not get build errors even though building is not needed in the first place.

Make sure your "fresh copy" is being put in an empty folder rather than on top of an older version.

Generally for custom development I recommend people to work with the mojoPortal source code not the pre-compiled release files, though it can work using the approach you are using. The source code uses a web application project type whereas when you open the pre-compiled release files in VS you are opening it as a web site.

Hope that helps,

Joe