Google redirecting to random spyware sites

So as the thread says, when i do a search in google, i go and click on one of the search results and it takes me to some random site that gets blocked by NoScript for being a dodgy website. I seems to happen randomly. Like I jsut went to check it there so i could get the link of where it sends me to, but it didnt happen. Sometimes it happens each link u click, sometime like just now not all all. I'm using firefox latest version. have done a spyware and virus checkwith a number of programs. only happens with when clicking on links in google search results. Has anyone esle noticed this? Anyway to fix it, it proper annoying