Article ID: 823441 - View products that this article applies to.
When you upgrade a Windows 2000-based computer to Windows 2000 Service Pack 4 (SP4), and then you remove SP4, scheduled tasks that you have created no longer run. When you view the status of a scheduled task, the following message is returned:
Status: Could not startWhen you view the log file that is created by the task scheduler (C:\WINNT\SchedLgU.txt), you notice information that is similar to the following: If you reinstall SP4, the scheduled task still does not run.
This problem occurs because of a change that is made to the data that is stored in the credentials database when you install Windows 2000 SP4.
When you install SP4, the data that is stored in the credentials database is converted to an SP4-compatible format. A registry key is configured to indicate that the data has been converted to the SP4 format. When you remove SP4, this registry key is also removed. This behavior occurs to make sure that subsequent SP4 installations convert the data to the SP4 format. However, the data itself is not changed, and therefore the credentials that are used to run the scheduled task are not valid when they are accessed by the earlier version of Windows 2000.
The Task Scheduler service also contains code to parse the credentials database, and this code removes any data that does not correspond to an existing task. Therefore, all the credentials that were stored under SP4 are removed by the earlier version of Windows. This housekeeping code starts 10 minutes after the Task Scheduler service starts and also starts whenever files are removed from the Tasks folder. Therefore, if you create scheduled tasks in Windows 2000 SP4, and then you remove SP4 to revert to the earlier version of Windows 2000, the credentials for scheduled tasks are removed if the Task Scheduler service runs for at least 10 minutes before you reinstall SP4.
To work around this issue, re-enter the credentials for each scheduled task. When you remove SP4 and then re-enter the credentials for a scheduled task, new valid credentials are created for the service-pack level of Windows that you are running. If you later install SP4, these new credentials are converted to SP4-compatible credentials.
Note If you want to remove and then reinstall SP4, and you have not already removed SP4, follow these steps:
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.