Adobe Flash Player plug in update

Hello.  I keep seeing a box that says my Adobe Flash Player plug in needs to be updated.  I've done this twice so far and still keep seeing it.  Then today, I saw a message that said "Norton's has prevented an unsafe plug in from running."  I also got a pop up from Norton's about an unsafe Adobe plug in (sorry, I don't remember the exact message).  I'm now worried I downloaded the unsafe plug in and am still wondering why some sites are still prompting me to update the Adobe plug in.  Any ideas?