I think it was in the late '80s. Micro$oft was sued by Netscape because their OS was more friendly to IE than Navigator and other browsers, and they claimed that MS was a monopoly, putting them out of business by giving away IE (Nav. was not free). I think MS had to release sections of their code or make it more browser friendly. Later, the US gov sued over the monopoly thing. And after their most recent lawsuit in the EU, new versions of Windows sold there now include a screen that explains that IE is optional (and I think it also lists alternate browsers).