I've had the Iplayer "loading" problem for about a month, and Samsung support have just resolved it over the phone and via a remote connection to the TV. They resolved it by resetting the SmartHub, changing the SmartHub country setting temporarily to the US, then changing it back again to UK. This is done via the menu option Smart Hub... Reset Smart Hub and then on the Terms and Conditions page entering a hidden combination of remote keys. That process presumably removes all the pre-installed apps then re-installs them, and that seems to do the trick. Details of the procedure to change the country setting can be found by Googling "How to Change a Smart Hub Region on a Samsung Smart TV" Hope that helps.
... View more