Just so I am clear you have the Sky box going via HDMI to out on the SKy box to HDMI IN on the SoundStand, then HDMI output on the Soundstand to HDMI IN on the TV?
The most likely reason is a software fault, however before we start resetting systems and patching etc, I would start by checking the cable going between SoundStand and the TV supports ARC, secondly the HDMI IN on the TV says ARC on it, and AnyNET+ is enabled.
You usually find with AnyNet you can control the soundstand with your TV remote so it may be this function which is causing it to freeze up, buy you should be able to use the original remote to control the soundstand.
Please take a look at the back of the TV and check your using the right HDMI (ARC) port, your using a supported cable and AnyNet is enabled on the TV.
I wouldnt worry about Anynet+ if your TV doesnt support it, it shouldnt cause an issue.
From checking the TV spec the Samsung series 5 TV's (which includes your models), does not support ARC, your TV is designed to connect to a external sound system by optical not HDMI.
I believe this is the issue, as the SoundStand is unable to communicate with the TV properly, I need to investigate this further to see if there is a way to overcome this issue.
I would suggest you plug the Sky Box directly into the TV, then connect the TV to the SoundStand by digital optiical fibre.
Your TV has a optical fibre output just under the HDMI sockets on the rear, and the Soundstand has a fibre input, this will remove issues to do with ARC, and still let you get clear sound, without causing it to lock up \ stop responding.
If you need anything clarified please let me know.