NAV picked up an intrustion attempt...now computer is slowing down

On the 19th while I was on face book norton antivirus came up saying there was a intrusion attempt HTTP FAKE AV INSTALL Request  4. It said that it was blocked so afterword I ran a full scan of my computer nothing showed up. Now my computer has been slower expecially while on the internet. Also when I was deleting my internet history I noticed two ip adresses which I thought was really strange. I wanted to know if its normal for ip addresses to appear in my internet history? Also is there a chance that my computer couldve been damaged by the attempted attack?

 

 

[edit: Clarified subject.]

 

Message Edited by shannons on 12-23-2009 08:34 AM