You're in a room with two doors and two computers. One door leads to death, the other to life. You can ask one computer one question. One of the computers lies and one tells the truth. What question do you ask the computer you choose?
This is so old it's not funny. It's just been modernized by using "computers" instead of the classic "knights and knaves".
Ask one computer which door the other computer would say leads to death, and then take that door. Either you're asking the truth-teller who will truthfully tell you the lie the other computer would tell, or you're asking the liar who will lie about what the truth-teller would truthfully say. Either way, the answer you get is a lie.