Hello.
Be caution, on some browser, ".gz" may be an extension associated to VRML plugin. If you have this association, the browser can try to extract the .gz file and run the VRML displayer.
If you use IE on Windows NT, remove the association in the "Folder Options" parameter.
If you use Netscape, remove the association in the "Preferences..." menu.
I hope it will help.
Commenter-1 Le Boité