qmake does not exclude additional files in resource folder from the build.

When using Visual Studio and having a project that includes .xsd files into an application dll's resources, then these files will be added to the resource folder. As these files are not excluded from the build, the project tries to generate header files and dlls for ADO.Net as though these were definition .xsd files for ADO DataSets.
To work around this you need to manually exclude these files from the build.