It's caused by the installer not setting the component_id in the xxx_menu table (replace 'xxx' with your database prefix).
For those who have found this error and don't know what to do, I did the following:
Locate the record in the xxx_extensions table for the 'gps_tools' component.
Make a note of the extension_id.
Locate the record in the xxx_menu table with the title 'GPSTools' and then set the component_id to the extension_id above.
Log into the admin menu and GPSTools should now appear in the list of components.
The administrator has disabled public write access.