Windows 95 let installers trash its files then fixed the mess behind their backs
(www.theregister.com)
Being the guy who had to feed the whole 32 floppy disk stack to the wretched PC every time the user broke the Windows 95 installation pushed me to the *nix camp quite early, I can tell you that.
Each floppy had a good 10% chance of being faulty, so imagine the fun.