Let me see if I'm following you right...
- You've got a laptop and a desktop
- You're trying to watch the Slingbox in CA from both computers
- Laptop is able to watch the CA box successfully when OUTSIDE your home network
- Desktop can not watch to the CA box at all
Is that all correct ?
If so, a little more information will help troubleshoot this:
- Can the laptop watch the CA box when INSIDE your home network ?
- Do you have your own Slingbox at home ? If so, can your desktop watch it ?
Any other details you think of might help too.
My initial thoughts are that either your Son's Slingbox in CA isn't set up for remote viewing, or your desktop computer has some security software running that is interfering with SlingPlayer. Those are wild, unreliable guesses until we can narrow down where the problem is happening at. Can't quite pinpoint it without some additional clues.
Post back when you have time, let's see if we can figure this out.