WAN vs LAN access problems

[Sears, Jeremy]

Hi All,
IM having a problem with my mapserver installation ....
I have mapserver/chameleon setup with ms4w on winserver2003.
 
When I view my application from our LAN (either localhost or another
computer on the LAN) the application works fine.
However, when I attempt to view the application from the WAN, chameleon's
elements work but neither the main map image nor the keymap image work. 
 
I have the entire ms4w package installed in in a location off the root like:
 
/adirectory/anotherdirectory/ms4w
 
 
Does anyone have any thoughts as to why the app works fine when accessed
from LAN but breaks when accesing through WAN?

Thanks
Jeremy