Rogue AI
Clarke puts a reason for the behaviour of HAL in the follow-up novel '2010'. HAL was just following conflicting orders as best he could when his programming had been tampered with i.e making the 'mission' (not necessarily the scientific one) more important than the crew.
I feel sorry for HAL. Being blamed when it was actually the fault of those pesky humans.
Biting the hand that feeds IT
