Was a problem that drove me a little nuts for a while .... they showed up in my VRML too as an annoying kind of flashing
Now as soon as I see that ring effect I know I have a hidden surface that must go ;-)
By the way Andy ... a little plug for AC3D :
http://www.3dworlds.ca/web3d/index.htm
Its done in VRML and you need a plugin to view it. Either Blaxxun Contact 5 or Bitmanagement 6+ . I don't recommend the *free* Bitmanagement 6+ as it has an ugly logo wanderering all over the screen
It does NOT work with the Cortona plugin as it uses a Contact specific VRML extension
The blaxxun plugin is available here :
http://developer.base.com/download/i.../install.shtml
griff