Sky max hub keeps flashing green

[as2001]

I have the sky max hub and last night it started flashing slowly green and this lasted for about half an hour and then returned to normal. Now again today it's done the same, both did this at different times. I've had the sky max hub for at least 2 months and it's worked great up until yesterday when it's started to do this. Any help? Yesterday I turned the hub off at the wall and the ont and when it turned back on it was still flashing green.