Norton blocked an attack notices

Over the last couple of days I keep getting notifivations in the bottome right corner of my screen from Norton re: blocked attacks, as in every few seconds.  When I click on the details, it brings up mumbo jumbo that I of course don't understand.  When I click on the history it shows tons of these attempted "attacks", many with a severety of "HIGH".  I'm a little freaked out...this has never happened before.  I feel like there is an all out assault on my computer.  Do I need to be concerned about this?  I'm the only person who uses this computer and I have not gone to any new sites or opened any weird emails.