In an interview for The Harvard Campaign (below) organised by the famous US university where Gates studied, the 57-year-old said a single button for users to press would have been a better solution.
Gates explained: "We could have had a single button, but the guy who did the IBM keyboard design didn't want to give us our single button...it was a mistake."
His honesty brought laughter from the audience, but Gates went on to explain that the three-keyed command was used as a surefire way of telling the computer its user wants to log in, and that it was used to prevent other apps from faking the login prompt and stealing your password.
Originally used to reboot the computer, the command was also chosen because it was impossible to accidentally enter with one hand, unlike the Ctrl-Alt-Esc first suggested by IBM engineer David Bradley, who then suggested the famous Ctrl-Alt-Del command instead.
Although no longer used to log in, the combination is still used to this day in WIndows 8 as a way of accessing the task manager to close unresponsive programmes, and as a shortcut to lock the computer, switch user, or change a password.
Not the first admission of mistake from the former Microsoft boss this year, Gates admitted during an interview with CBS This Morning in February that his company didn't take command of the mobile market when it had the opportunity.
"There's a lot of things like cellphones where we didn't get out in the lead early. We didn't miss cellphones, but the way that we went about it didn't allow us to get the leadership," Gates said, adding that this strategy was "clearly a mistake."