Try out this if you wish to remove the "Standby" option from the Windows XP.
Begin by clicking on the "Start" menu on the taskbar. Followed which, click on "Run".
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In the "Run" window, type: regedit and click on "OK"
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Navigate to:
HKEY_LOCAL_MACHINE \SYSTEM \ CurrentControlSet \ Services\ ACPI\ Parameters
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On the right side of the window, right click, select
"New" and then click on "DWORD Value"
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Right click on the value to
rename it as "Attributes".
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Double click on "Attributes" to set its "Value data" to 70. Make sure that 'Hexadecimal" is selected.
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Click
on "OK"
, exit the Registry editor, and reboot.
Now the next time when you Turn off your computer, you won't see the option "Standby".