ArcToolbox tools do not start when double-clicked

Description

When ArcToolbox tools are double-clicked, nothing happens or a brief hourglass appears.

Cause

Microsoft XML parser 3.0 Service Pack 4 (SP4) or XML Core Services 4.0 are not installed or have been removed since the installation of ArcGIS 9. This prevents the dialogs from being generated or displayed.

Solution or Workaround

Note:
Even if the XML parser 3.0 and XML Core Services appear to be installed, rerun the install for both of these components; this will replace any files that may be missing or corrupt.