Actually, I think we found the problem.
In IIS control panel, there is an option for permitting/denying certain extensions for executables. By default, ASP (and ASPX) seems to be turned off.
We turned it on, then got an error message that the application could not write to the temporary directory for ASP files, and had to grant those permissions to the appropriate system user.
Now it works.
Perhaps the Install could check that IIS permits the extensions used in the web console and either fix it or print an alert to the admin doing the install???
(of course this probably only occurs when installing on a machine that hasn't been used as an actual webserver before -- if you run an actual website on MS IIS, presumably you would already have needed to enable asp/aspx extension 🙂 )