I think you're thinking of Windows Longhorn (https://en.wikipedia.org/wiki/Development_of_Windows_Vista#M...). They used managed code and ended up partially scrapping it to restart development on top of Windows Server 2003.

Windows ME was just Win98SE in an ugly sweater. Mostly C/C++ with some assembly peppered in.

Maybe you’re thinking of this?

https://en.m.wikipedia.org/wiki/Singularity_(operating_syste...

Servo relies on firefox's JS runtime spidermonkey, written in C++.

Moreover, a significant fraction of JS vulnerabilities are logic errors in the JIT, so even if the JIT itself is memory safe, that doesn't make the resulting code free of vulnerabilities.

Windows ME was the worst Windows though.

Hard agree.

Windows 98SE SP2 was the best

Vista was the worst in my book. And Vista was actually the real turning point when C# started to infect Windows.