proxy / server problem

I am using Image Uploader Java version 2.5.4.0 and ActiveX version 4.5.4.0 and have valid licenses for both. On any home computer both applets work correctly on the client side. When used in some corporate environments (client side), only the ActiveX version works and I get the "The server or proxy [Name] not found" for the Java version. In the Java environment that it is not working, I am using Windows XP SP2 and firefox 2.0.0.6. I have had this problem independent of any iu.addParam settings I pick.