You may not be able to start the SQL Server Agent Service for your instance of Microsoft SQL Server 2000 or of the Microsoft SQL Server 2000 Desktop Engine SP3 (or later). This problem may occur when all the following conditions are true:

1.	One of the following actions occurs: • You remove an instance of the SQL Server 2000 Desktop Engine SP3 (or later). • You remove an instance of the SQL Server 2000 Desktop Engine (Windows).
2.	You install an instance of the SQL Server 2000 Desktop Engine SP3 (or later) or SQL Server 2000.
3.	The instance name of your current instance of the Microsoft SQL Server 2000 Desktop Engine SP3 (or later), of the SQL Server 2000 Desktop Engine (Windows), or of SQL Server 2000 is the same as the instance name of the previous instance of the SQL Server 2000 Desktop Engine (Windows) or of the SQL Server 2000 Desktop Engine SP3 (or later).

To work around this problem, remove the following registry key manually after you remove the instance of the SQL Server 2000 Desktop Engine (Windows) or the SQL Server 2000 Desktop Engine SP3 (or later): To do this, follow these steps:

Warning If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

1.	Click Start, and then click Run.
2.	In the Open box, type regedit.
3.	Click OK.
4.	In Registry Editor, locate and then select the following registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\<InstanceName>\SQLServerAgent
5.	In the right pane, locate the GUID registry value, right-click the registry value, and then click Delete.
6.	Close Registry Editor.
7.	Start the SQL Server Agent service.

Note You may notice that you can start the SQL Server Agent service after you remove the registry key.

Microsoft has confirmed that this is a bug in the Microsoft products that are listed in the "Applies to" section of this article.

When you try to start the SQL Server Agent service, the startup code for the SQL Server Agent service verifies whether the following registry value exists: If the registry value exists, the SQL Server Agent automatically quits. The SQL Server 2000 Desktop Engine SP3 (or later) and SQL Server 2000 support this feature. Because the registry value is not removed when you remove the SQL Server 2000 Desktop Engine (Windows) or the SQL Server 2000 Desktop Engine SP3 (or later), the problem that is mentioned in the "Symptoms" section of this article occurs.

The SQL Server 2000 Desktop Engine (Windows) does not support the SQL Server Agent feature. Therefore, when you install the SQL Server 2000 Desktop Engine (Windows) with the same instance name as the instance name of the previous instance and then the registry value for the previous instance is not removed, the functionality of the current instance is not affected. If the instance of the SQL Server 2000 Desktop Engine (Windows) is upgraded to SQL Server 2000, the GUID registry value must be manually removed. Therefore, after the upgrade process, you can start the SQL Server Agent service.