NOTE: This is relevant to IIS 6 only.
One of the features of IIS 6 is that it allows a greater level of what application extensions are made available on the server. However, in some cases you may find that while the appropriate version of ASP.NET is installed on your server, it is not allowed. One example of this might be receiving a blank page (or a 'page cannot be displayed' page) when browsing to the application.
To configure web service extensions, open up the IIS 6 manager, then browse the the 'Web Service Extensions' folder (this should be on the same level as the 'Web sites' folder). Ensure that the 'ASP.NET v2.0.50727' item is enabled.
NOTE: If you are attempting to run the HelpMaster Web Interface on a 64 bit machine, there are a number of other considerations that must be given attention. For more information, please see the article on configuring the web interface for 64 bit servers.