1408

Mike Enslin (John Cusack) is a cynical, skeptical author who, after the death of his daughter Katie (Jasmine Jessica Anthony), writes books appraising supernatural events in which he has no belief. After his latest book, he receives an anonymous postcard depicting The Dolphin, a hotel on Lexington Avenue in New York City bearing the message, "Don't enter 1408." Viewing this as a challenge, Mike forces the hotel to allow him to book the room, referencing a law that any hotel room in New York can be requested as long as it meets safety standards. The hotel manager, Gerald Olin (Samuel L. Jackson) tries to dissuade Mike from checking into the room, explaining that 56 people have died in the room over the past 95 years, and that no one has lasted more than an hour inside it. Mike, who does not believe in the paranormal, insists on staying in the room, and asks Olin if he thinks it is haunted; Olin replies that it is "evil" rather than haunted.
Once inside the room, Mike describes on his mini-cassette recorder the room's dull appearance and its unimpressive lack of supernatural phenomena. During his examination, the clock radio starts playing "We've Only Just Begun". Mike assumes that Olin is playing a trick to scare him. At 8:07, the song plays again and the clock's digital display changes to a countdown starting from "60:00". Mike experiences a series of supernatural events. A window sash slams down on his hand, the hotel operator calls about food he didn't order, and ghosts of the room's past victims and members of his family, particularly Katie, appear on the TV set. Mike's attempts to leave the room are in vain; the doorknob breaks off, climbing through the air ducts prompts an attack from the corpse of a former room victim, and climbing onto the window ledge reveals the windows of the other rooms have disappeared.
Mike uses his laptop to contact his estranged wife, Lily (Mary McCormack), but the sprinkler system short circuits his laptop. The room temperature drops to subzero when the laptop suddenly begins to work again, and Lily tells him the police have entered 1408, but the room is empty. A doppelgÃ¤nger of Mike appears in a video chat window and urges Lily to come to the hotel herself; it gives Mike a wink. The room shakes violently and Mike breaks a picture of a ship in a storm. Water pours from the broken picture, flooding the room. He surfaces on a beach and relives a surfing accident seen earlier in the film. His life continues from this point, and he reconciles with Lily. Eventually he assumes his experience in 1408 was just a dream. Lily persuades him to write a book about it. When visiting the post office to send the manuscript to his publisher, he recognizes members of a construction crew as the Dolphin Hotel staff. They destroy the post office walls, revealing Mike is still trapped in 1408. A vision of Katie appears to Mike, and after some reluctance he embraces her; she crumbles to dust. The clock radio begins playing "We've Only Just Begun" again, and Mike looks for it in the rubble. It counts down the final seconds. When the countdown ends, the room is suddenly restored to normal, and the clock radio resets itself to 60:00.
The "hotel operator" calls Mike again. When Mike asks why he hasn't just been killed already, she informs him that guests enjoy free will and that as such he can relive the hour over and over again, or use their "express checkout system". A hangman's noose appears and Mike has a vision of himself hanged, but he refuses to kill himself. Mike improvises a Molotov cocktail from a bottle of cognac given to him by Olin, and sets the room on fire. The fire alarm sounds, the hotel is evacuated, and Lily is prevented from entering. Mike breaks a window, causing a backdraft. Mike lies down upon the floor and laughs in victory upon destroying the room, eventually perishing in the flames.

Question: What short circuits Mike's laptop?
Answer: Sprinkler system