Sims 4 Play Button Greyed Out

My niece has got the Sims 4 installed from a CD we purchased in a Game store.  It was working absolutely fine for ages and now all of a sudden in the past few months or so she can't click on the Play button as it's greyed out.  She's only got the game installed on her 1 laptop.

I've tried updating the game, installing any patches that are available, reboot the computer but nothing.

I've also cleaned out the cache via the instructions given on forums here and through online searches.  The game will work after a reboot but it only lasts for a short while before the Play button greys out again.

I only cleared the cache out a few weeks ago and my niece has called again telling me it won't let her play it again.

Anybody got a fix or at least a long term solution for this?  It's driving us all crazy.