If your box is more than a few months old and you haven't updated then you could do this to see if it helps.
Go to the two cogs and click here, now go apps and let it load. Now look for the OTA updater app and click here. Now force stop and then clear data and wait while it finishes.
Go back and try again see if this works, if you've updated in the last few weeks then you are fine. T8-S plus only...