If you are surfing the web and click on a file of type DVI, you probably want to view that file. If your browser (e.g. Netscape) does not start a DVI viewing program, you want to tell it how.
In Netscape 4, go to ``Edit - Preferences...,'' choose ``Navigator - applications,'' and edit the application called ``TeX DVI data.'' It should be handled by the application ``/usr/local/bin/xdvi %s''. If you make those settings changes, then Netscape will run the program xdvi to view any DVI files.