Regarding your issue there could be several possible factors causing this. This could possibly be caused by the Slingbox possibly being frozen and needing to be power cycled. It could also be the cable box itself that is frozen and may require a power cycle as well. If the issue is not remedied by either attempt than the Slingbox itself may need to possibly be factory reset. Below is an article elaborating on how to do this.
Hope This Helps!!
Shortly after connecting to our slingbox this morning it froze on the scene it was on and did not change. After trying to connect 10 hours later it is still frozen on the same screen. I tried connecting with three different browsers (Firefox, Chrome, Explorer) and there was no change.