.NET 3.5 apps crash, Safe Mode display flickering

The April preview update broke .NET Framework 3.5 applications — a theme that would repeat for months to come. Safe Mode, the diagnostic mode you boot into when Windows is broken, developed display flickering and explorer.exe instability. So when the update broke your apps, and you tried to boot into Safe Mode to fix it, Safe Mode was also broken. Some users encountered BSODs during installation. Microsoft had managed to break both the normal operating mode and the emergency diagnostic mode in the same update.