Bad pool header causes activated laptop to deactivate

I had problems with my laptop this morning where I got the blue screen saying there is a problem and windows needs to shut down due to this Bad Pool Header problem, it kept doing this so I had to refresh the laptop condition as it wouldn't even do a System Restore now after the refresh it now asks me to activate my version of windows as apparently my product key is being used on another PC, but this laptop has been activated for over 3 years so I really don't understand why it's now asking me to activate windows again.

TBH i'm not too computer savvy so don't know how to get into logs etc.