I work on the CLR/BCL team and just answered your email. Here it is pasted below: Jared's answer on Stack Overflow is right on. mscorlib.dll is tightly bound I am running into peculiar issue. I am developing a windows based application which connects to Oracle database. For initial testings, I have created installer. Meta.Numerics is a library for advanced scientific computation in NET Framework. Do you know why hxds.dll is loaded without asking the user beforehand. When you are registering a DLL in old machines (Windows XP), regsrv always says that the registration was sucessful. This happens even if the user doesn't.