“Wake the computer to run this task” function in Task scheduler may not work as expected


Consider the following scenario:
  1. You have enabled "Allow wake timers" setting on current power policy in Power Options item in Control Panel. 
  2. You set a Scheduled Task to wake the computer 1 month and 10 minutes later:
    For example, If the current time is 7/14/2011 PM 4:48. You can set a scheduled task to 8/14/2011 PM 4:58 with the following setting on the "Conditions" tab:

    “Wake the computer to run this task” checkbox checked
    "Start the task only if the computer is on AC power" checkbox unchecked
  3. You put the computer into sleep.

You may find the computer wakes up 10 minutes later instead of 1 month and 10 minutes later. You may also see the following event log entry in system event log:

Log Name:      System
Source:        Microsoft-Windows-Power-Troubleshooter
Date:          7/14/2011 4:58:19 PM
Event ID:      1
Task Category: None
Level:         Information
User:          LOCAL SERVICE
Computer:      <COMPUTERNAME>
The system has resumed from sleep.

Sleep Time: ‎2011‎-‎07‎-‎14T16:51:29.943417800Z
Wake Time: ‎2011‎-‎07‎-‎14T16:58:00.770507800Z

Wake Source: Unknown


Some platforms do not support RTC timers on monthly/yearly basis settings. If they do not, the machine may determine the wakeup time incorrectly.  


Please contact the original hardware vendor to check the supportability of the RTC timers for different platforms.

More Information

According to ACPI SPEC 4.0, hardware vendors can choose to support RTC timer on monthly/yearly basis implementation. For more information please refer to the ACPI SPEC 4.0


Article ID: 2586195 - Last Review: Aug 22, 2011 - Revision: 1