When I attempt to open such a file by selecting [tt]File > Open Page > Choose File...[/tt] or by entering a [tt]file:///[/tt]... URL into the location bar, I instead get a dialogue informing me that Communicator needs to spawn an external viewer, and the page then proceeds to load in my default browser, Mozilla Firefox.
In the Navigator > Applications section of Preferences, Communicator is set to handle HTML files by "Netscape (internal)," so I don't really know why this is happening.
This has never happened to me before, and it does not affect my installations of older Netscape versions such as 3.04.
This makes it extraordinarily difficult for me to test to see how local HTML documents render in Communicator.
UserAgent: Mozilla/5.0 (Windows; U; Win95; en-US; rv:1.7.5) Gecko/20041107 Firefox/1.0

