Just to make sure we have the other obvious base covered, your Folder Options dialogue should have the "Hide extensions for known file types" option unchecked. (See attached image; ignore the WindowBlinds skin. Yeah, I like custom interaces, shocking, eh?
![Wink](/images/style_mmoi_eq2i/smilies/wink.gif)
)
If the option is checked uncheck it and verify that the file isn't actually icon_map3.dds.dds.