Yesterday, I noticed that I was unable to use google. Also, my laptop was working really slowly and quite often, pages wouldn't load at all. I did some spyware and virus scans and it turned out that i had a trojan virus

I stuck it in the "virus vault" and thought that it was the end of my worries. Later on, I realised that google still didn't work and lots of pages still wouldn't load for me. I did that same virus scan again and nothing came up. I have been struggling with this problem all day, can anyone shed some light on it?
Summary of things i've noticed:
1)Slow laptop
2)Some pages not loading at all
3)Able to visit
http://www.google.com, but unable to actually use the search engine
4)Trojan virus supposedly deleted
5) Still had the same problems.
Any help would be great.