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William I wouldn't do that - make sure to just noindex tags, and also noindex subpages of archives. Categories can stay indexed, it's usually the subpages that cause issues (ie: /page/2/ etc). -Dan

Hi giankar, you are not alone, my site was also affected... 50% loss. Here is my thread: http://www.seomoz.org/q/lost-50-google-traffic-in-one-day-panic Here are some tips and tricks: http://www.seo-stories.com I hope, that helped a bit. Best wishes, Georg.