If something happens to a shared DLL file, either it goes missing or gets corrupted in some way, it can generate a 'runtime' error message.
Unfortunately, what makes DLL files so convenient and efficient, also makes them extremely vulnerable to problems. FL Studio) could share the same Fruity Envelope Controller.dll file, saving valuable memory allocation, therefore making your computer run more efficiently.
These files were created so that multiple programs (eg. Dynamic Link Library files, like Fruity Envelope Controller.dll, are essentially a 'guide book' that stores information and instructions for executable (EXE) files - like mrt.exe - to follow.
Fruity Envelope Controller.dll is considered a type of Dynamic Link Library (DLL) file.