Svchost.exe is a container of sorts that contains and controls the running of various services/programs grouped logically together in a svchost.exe process. It contains only what the OS loads into it as services and programs are started.

What Web Browser are you using?

In the past I have had problems with redirects in Firefox though I am sure that people get them in IE, Chrome, Opera etc. As I recall I finally located the problem in one of the addons and was able to fix it. It was nasty and took quite a bit of time to find it and get rid of it. Avast and other virus scanners did not detect it. I only found it by sheer luck persistence and a little experience.