ThinScript.dll is my COM interface to the Windows Script subsystem, including the Windows Script Debugging interfaces. This makes it possible to debug scripts within ACP’s console and have them show up in Visual Studio Script Debugging. The interfaces are extremely complex and poorly documented. I had to get help back in 2001 from Microsoft and they were amazed at what I had done to expose it all to COM and thus Visual Basic. This has all been totally untouched for many many years and is supporting over a thousand ACP installations on all versions of Windows back to XP. It is the workhorse of ACP and has millions of miles on it. You’re seeing errors from the Windows Script (and maybe something else that supports Windows Script) coming through ThinScript without any COM source because the errors are coming from Windows. Thus the “source” is ThinScript since the real source is unknown.