Just a moment... Just a moment...
"Rogue AI". HAL was merely a computer with flawed programming operated by humans who insisted in inputting data that was out of bounds for the application.
HAL was given contradicting instructions. Provide all the information the crew needed to perform the mission and keep the true goal of the mission a secret. When Dave and Frank start interrogating HAL (which they should have known better*) they exposed the flaw.
To HAL it became an equation to be balanced in which humans were a variable. He balanced the equation by removing the crew from the equation. Thus exposing the second flaw; a lack of an instruction to value the life of the crew above all else.
Many people miss it. Where HAL repeats "Just a moment" is when he is trying to solve the equation. This is the pivotal and most underrated moment in the film. HAL is the fastest computer known to man. He can instantly retrieve any data or solve any problem without delay, but takes not one but two "Just a moment" when Frank and Dave ask their question. This is an eternity in terms of processing time. It indicates all of HAL's resources went busy trying to solve the equation and come to the most unfortunate of solutions.
So, as HAL himself states, it has always been due to 'human
error'.
* - Frank and Dave are both military. Their training wouldn't allow them to interrogate another crew member about potentially classified information. They did not truly view HAL as another member of the crew.
Biting the hand that feeds IT
