Since I don't have access to the Callidus Portals available on various websites, I can recommend the following regarding your issue:
Always try Internet Explorer. Even no one accepts it, it gets things done because it has support for ActiveX and most of these portals run or use ActiveX technology.
Make sure that your Java is always updated to the latest version and the website that you are trying to access is verified and added to Exception list.
Note: The website in the list, as you see in the image, is allowed to run Java code on my PC, that's why it's added there. You should edit the list on your PC and add the website you're using to load the ports. Make sure to add HTTP or HTTPS because it makes a difference.