It may happen that when installing TimeTrust you receive the following message:
HTTP Error 500.19 - Internal Server Error
The requested page cannot be accessed because the related configuration data for the page is invalid.
This message is possibly due to an installation problem with MS IIS set up
Please confirm that Application Development features have been installed on the server - see image below:
Once these features are installed you may be required to restart the server for the features to come into effect.