Installer have been a tricky part for NaroCAD because NaroCAD is a .NET/C# based CAD application and when it crash that is missing dlls, etc. it will throw a C++ exception that is not possible to catch from C#. Also, some files are not obvious in OpenCascade usage as they were not dlls.
This was happen to be the first two problems. The last problem was that at least in the past it was considered as fact that NaroCAD have some dependencies supplied and if not NaroStarter will detect them. Because the installer should provide the Dlls without installing the corresponding applications, will make NaroStarter to not detect the environment problems as for certain there are no dlls implied.
Thus makes needed more changes and the hardest problem was that at any given time was needed to be tested under a virtual machine to make all things testable, making more than running a program and attaching the debugger.
But all things seems fixed right now. The installer right now grows to 16M as it comes with OpenCascade part inside. The single dependency (excluding Windows) is .NET 3.5. If you have updated Windows Vista or Windows 7, you will have them, if not (so you have Windows XP) you will need need to download it explicitly.