I have a similar problem. When i go to the website slingbox.com to stream video, it initializes and then starts to stream perfectly. Then in a couple of minutes the picture freezes and goes black and I only have sound. This happens on 4 computers and in safari AND firefox AND chrome. However 2 of those computers have the old icon for slingbox -- the one you click on and it goes immediately to streaming. The icon works perfectly and keeps on working !!! But the www.slingbox.com doesn't. Tech support has been very UNhelpful!!!!
As for your problem -- I understand you can push reset to reset the slingbox and thay MAY help
It seems that you are having some issues with your Slingbox PRO-HD since although it shows solid lights, you are not able to locate it on your network.
Most of the times, this issue might be related to a wrong OS and web browser version combination. With this in mind, I encourage you to check the following link in order to determine if your computer meets the requirements:
Hope this helps!