In .Net assemblies are stored in %WINDIR%\assembly\ and the Runtime is in %WINDIR%\Microsoft.Net\Framework\version.xxx.xxx\ so it's not neccesary to call some API to get the COM directory (so it still seems to be null).There are simple methods and namespaces in .Net like Environment.GetEnvironmentVariable to retrieve the assemblies directory and "hardcoded" it in the .dll/.exe.Not that linking of .dll and assemblies can also be done on the fly in .Net while the .exe is running..

I'm going to have a look at it too and let you know if i find something.