After I plug in the VGA cable,

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After I plug in the VGA cable, I turn the laptop on and then turn on the monitor. The monitor shows the same thing that's on the laptop's screen when it's starting up. But when it's done, the PC monitor shuts down before it gets to the Log in screen. How can I fix this problem?

[edwin]

check the manual of the laptop for the special function switches at the top of your keyboard, in there you should be able to select, laptop screen, monitor or both (if supported).