The links on the search results were being hijacked and I was being redirected to non related sites. This was a huge pain as I use search engines constantly every day. This happened with every search engine I used, not just Google.
I would search for silver powder and would get a list of actual suppliers, but when I would click on the link, I would get redirected to a home loan scheme or a link farm of some sort that had nothing to do with my search terms.
My Avg systen was blissfully unaware that anything was wrong and showed nothing out of the ordinary.
I downloaded and installed Microsoft Security Essentials and in 4 minutes it had spotted a file called: Win32/PossibleHostsFileHijack and I was able to download a fix from the Microsoft site in minutes and it cleared the problem up immediately.
If your searches are going astray, you might want to check out Microsift Security Essentials.