This often happens to me, but I find that if I just restart my browser then it's all fine.
When that doesn't work, it's just a case of waiting for it to stop.
I never have to wait more than a day, but if your friend's hasn't been working for more than a few days then you might have a different problem.
I realise that this isn't too helpful, but I just wanted to let you know that I'm familiar with this happening and how I deal with it :3
Good luck to you and your friend!