I've always been a firm believer that having a perfectly XHTML coded site and not using tables for layout has no effect on ranking vs a properly formated HTML site using bulky tables. I've been able to see this first hand with a site I recently purchased. This site had horrible coding. The HTML was not only overly bulky and used nested tables but in many places, there were unclosed tags which Dreamweaver would choke at at trying to render. Not only was this bad for redesigns and layout maintenance but made the site fairly slow to download and render so I went about cleaning it up. I got rid of the tables, rewrote overly verbose HTML with clean, simple markup and proceeded to upload the new site. It took all of 3 days before the traffic started to decrease. Within a week, the site had lost over 60% of it's traffic. My use of search result rank checking software confirmed that the site had dropped many, many spots in rank for it's target terms. So, I uploaded the old, crappy, bloated HTML and within 6 days, the site's traffic and rankings were back to normal. I re-uploaded the new design and saw the traffic dip once again. Since then, I've been making very small changes, one at a time to try and see what exactly is causing the problem. Keep in mind, none of the content or linking was changed. Only the HTML tables were replaced with DIV tags and new CSS classes created. Also of note is that this wasn't a few day decrease in traffic. Once I let it sit for 2 weeks and it just got worse until the traffic leveled off at about 30% of it's original. I have noticed that some of the recent, small changes of replacing parts of the design with DIV tags has resulted in about a 10% increase in traffic. I'm to the point where it's not practical to try and make any more small changes and will try to upload everything again. Anyone else noticed this strange Google treatment of cleaned up sites? I would assume that since the site loads much faster and has proper syntax that this would only help but time and time again, I've seen the opposite. I want to do a total site redesign but don't want to waste the time if it's going to kill the site's traffic. Any ideas?