Bill Gates has called the decision to use Ctrl+Alt+Del as the shortcut to log on to a PC a mistake.

The Microsoft founder also blamed an IBM engineer for the three-finger command, which still exists in the Windows 8 OS as the way to bring up the task manager toolbar.

However, tens of millions of computer users use the shortcut daily to log on or lock their screen at work and home.

The keyboard manouvre was invented by IBM engineer David Bradley, who found his initially preferred method of Ctrl+Alt+Esc was too easy to accidentally bump the left side of the keyboard and reset the PC.

The Del solution ensured most users would perform the operation with two hands, meaning it was nearly impossible to execute the command accidentally.

But Bradley – revered by programming fans – credited Gates with making the shortcut famous.

However, speaking at a Harvard University-staged fundraising campaign recently, Gates called it a mistake to not have a single button.

"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," he said.

Gates is the world’s second richest man with a fortune valued at $67bn, after donating another $28bn through the Bill & Melinda Gates Foundation.