What I'm getting from your post, is that you're having problems streaming video from the iPad.
First of all, are you having the same problem from the computer's SlingPlayer?
Besides that, is the problem under one specific network? 3G or WiFi?
Now, one thing that you can try, is to remove the application then download it back, if still the same problem after that, you can run the Slingbox Setup Assistant from the computer, to save the video settings once again.
If the problem is still the same after that you can post the results here.