Virus? or Hardware?

Hi. I have a hp laptop and have just encountered two trojans. unfortunately i am an idiot and forgot to check which viruses they were and just deleted the infected file. after a full scan nothing was detected but my lap top still show some unordinary symptoms. my internet stops working every 10-15 minutes. the connection icon on the tool bar shows that it is still connected but nothing works. i hve to reset the internet to get it to work again.

also i was wondering if there is a way to back track and see what virus it was that was detected. I am currently using the mcafee software.