When using the ArcGIS Server 9.3 .NET Web ADF with Visual Studio 2008, the following situation may be encountered: the first task added to the Task Manager cannot be selected or fully configured by opening the Smart Tag menu.
The following image displays an example of successfully selecting and opening the Smart Tag menu.
This is a known issue.
Another workaround is to temporarily add a second task to the Task Manager. This allows the first task to be selected and configured. Once complete, the unnecessary task can be deleted.