hmmm, I'm assuming you are using watch on slingbox.com?
I think perhaps deleting and redownlaoding the Slingplayer plugin might be the best next step to try.
This article: Installing/removing browser plug-in for Watch on Slingbox.com walks you through the steps.
Let me know if that helps,
I have the Slingbox Pro HD. One day everything was fine watching video on my MacBook Pro. The next, I have audio, but NO PICTURE.
The box must be okay, since all is well on my phone and tablet. I've tried deleting cookies and resetting up, but to no avail.
Anyone have any suggestions, or experiencing this same issues. What to do? Btw, Safari is my browser on all of my devices.