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To create a shutdown timer manually, open Command Prompt and type the command shutdown -s -t XXXX. The "XXXX" should be the time in seconds you want to elapse before the computer shuts down. For instance, if you want the computer to shut down in 2 hours, the command should look like shutdown -s -t 7200.
If you want to restart your computer on a delay, use shutdown -r -t XXXX instead. Nice, Simple Short-cut Puts Shut-down Timer on Windows [cnet.com]