Thank you for using the answers forums. Sorry to hear you are having an issue with your PRO-HD. Has this issue happened at more than one location? It sounds like this issue may be related to the network. The first thing to check would be the upload and download speeds. You would need a 2 mbps connection upload at the Slingbox location and a 2 mbps connection download at the viewing location. You can also try a different location to see if the same issue persists there. You can also try to hard reset the Slingbox and set it back up using the website setup.slingbox.com to see if this fixes the issue.
Hope this helps,
The Sling Moderation Team