Oh it gets better (not the OP but I think the following is even worse).

That DLL hooks into SCADA and sometimes sends updates to a PLC controlling safety critical equipment. When does it send updates versus just query the controller? No one knows. The guy who wrote it died in an (unrelated) industrial accident involving a runaway forklift after leaving the company. Even so much as debugging it would require shutting down the entire factory and replacing all the crucibles afterwards ($$$).