Bill Gates on the legendary Control-Alt-Delete:

Microsoft co-founder Bill Gates has finally admitted that forcing users to press the Control-Alt-Delete key combination to log into a PC was a mistake. In an interview at a Harvard fundraising campaign, Gates discusses his early days building Microsoft and the all-important Control-Alt-Delete decision. If you’ve used an old version of the software or use Windows at work then you will have experienced the odd requirement. Gates expains the key combination is designed to prevent other apps from faking the login prompt and stealing a password.
Before Control-Alt-Delete was used to log into Windows machines it was how you restarted the whole computer. My father taught me this back in the pre-Windows days of the early 80s.
In middle school I taught this trick to my friend Dave. When we went to the mall we would reboot all the computers on display in Sears and then run out. The sales people on the floor were usually computer illiterate and had no idea what we had done.
It didn’t take much to keep us amused back then.