Unable to access the internet and SuperAntispyware scan results found 3 critical threats

Hi,

I am unable to access the internet on my PC. I can connect to my home broadband but when I try to surf the internet on IE or Firefox web browsers they both show a blank page and become unresponsive. I cannot update my Norton 360 AV as it keeps encountering an error.

SuperAntispyware scan results found 3 critical threats: -
Trojan.Agent.Gen
Backddor.bot[ZBot]
Malware.Trace

Tracking objects: -
Adaware.tracking cookie

I would appreciate it if you could advise me on how to get rid of these...

Unable to access the internet and SuperAntispyware scan results found 3 critical threats