[ishaanbahal]

I think your neighbours machine went into some issue and did an automatic restore to some working state, which probably was the first login state. The files remained but the rest of the software got removed that probably don't ship with Windows. So maybe this one was not MS trying to remove your open source browsers, but just doing a system restore using an image.

[squarefoot]

A system restore from an image would wipe everything, luckily all user documents were intact, including user login, password and desktop background. But all personal data pertaining to 3rd party browsers was gone (all passwords, all bookmarks) which suggests that an algorithm decided that something in the user folders had to stay and something else had to go.

[colemickens]

Sounds like Windows 10's "Fresh Start" feature. https://www.microsoft.com/en-us/software-download/windows10s...

I could easily imagine someone stumbling onto this and running it. (Windows Security -> Device perf & health -> Fresh Start).