PRB: "Invalid class string" error message when opening DTS package (288910)

SYMPTOMS

When you try to open a Data Transformation Services (DTS) package in the Enterprise Manager DTS Designer, you may receive the following error message:

Error Source: Microsoft Data Transformation Services (DTS) Package
Error Description: Invalid class string.

If you try to open the package in SQL Server 2000, you may also receive the following error message:

The selected package cannot be opened. The DTS Designer has been closed.

CAUSE

This error message occurs when the class identifier for a DTS task has not been registered properly with Windows. Because DTS tasks are registered with Windows using a COM class ID (CLSID), if that identifier is not present, a package that includes these unregistered tasks will not open. This error may occur in the following situations (note that this is not an exhaustive list):

A package includes Microsoft OLAP Services or Analysis Services tasks (such as the Data Mining Prediction task or Analysis Services Processing task) but the workstation on which a user attempts to open the package does not have either the OLAP or Analysis Services management tools, or the DTS Task Kit installed.
A package includes new SQL Server 2000 tasks (such as the Execute Package task or the Dynamic Properties task) and a user attempts to open that package with the SQL Server 7.0 management tools.
A package includes a user-designed custom DTS task but the workstation on which the package is opened does not have this task registered.

WORKAROUND

The solution to this problem depends on the type of tasks that are present in the DTS package. Because these tasks (and their associated class IDs) must be registered with the operating system, this problem is usually alleviated by an installation of the components in question:

If the package includes an OLAP Processing task from a SQL Server 7.0 server, you must download OLAP 7.0 Service Pack 3 (SP3). The DTS Task Kit (DTSTasks.exe) is included with OLAP 7.0 SP3. To download OLAP 7.0 SP3, visit the following Microsoft Web site:
http://www.microsoft.com/downloads/details.aspx?FamilyID=f62f45e9-24ed-4fa6-bd74-8a26606f96d8&DisplayLang=en
If the package includes other tasks shipped with Microsoft SQL Server 2000 Analysis Services, you must install the Analysis Manager component that is available during SQL Server 2000 Analysis Services setup.
In the case of tasks newly shipped with SQL Server 2000, you must install the SQL Server 2000 Client Tools on the workstation in question.
If your package contains custom DTS tasks, you must register these tasks on the workstation in question.