Product Key Revoked after update installed

I have just installed a Norton software update after a window from Norton popped up requesting me to do so.  When it was finished I was asked to re-start.  I clicked on the Norton re-start button and it did re-start.  After logging on I received the message 'Revoked Product Key' and that led me to this Community. 

I have Windows XP and I have Norton Internet Security 2010 with a 2 year licence from 27 november 2009 - almost 11 months to run.   

The only possible influence I can think of might be that yesterday I ran Advanced System Care to improve the response of my computer. After running this however I used the computer for a long tome without problem.  The update triggered the problem.   

How do I have my Product Key reinstated?