Why did I have a trojan when I use Norton 360?

My computer would not boot up this moring and has been running slow lately.  I finally got it to boot and immediately did a full scan.  It shows 2 things I am concerned with #1 It said I had Trojan.Zbot and Trojan.gen.2 - how am I getting trojans when I have Nortopn 360 running all the time?? Now that it is detected....did it6 get into my norton vault or anything I should be concerned with?

 

 

#2 why am I getting tons of " An intrusion attempt by (deleted) was blocked" - I'm glad its blocking them but they are coming in every 5 seconds - literally.  What can be done about this and cant they system block this persons ISP?

 

Thanks

Kat    :catvery-happy: