I'm a bit stumped if my machine picked up some malware infection, or is
Yahoo and a few other sites pulling something new ?

For the last week or so, I do a search at Yahoo.com, and pages
intermittently get re-directed to strange link pages or sales sites.

Noticed when I try to go back (using the back button), there are often
several strange pages in the history after the page I was at.
Some actually do say "re-direct."
Yet ran several scans on my system using several anti-mal/spyware's and no
malware is being found.
Also often noticing the same thing at Amazon.com.
Yet other websites show no problems at all.

So is my system infected with some rare redirection trojan, or, are some
sites getting really ignorant with the ad's ?