I understand that there is volatility in SERPs for a thousand different reasons, but lately I haven't been able to wrap my head around what I'm seeing for a couple keywords on one of my sites (5 months old). I've been using RankTracker to monitor my position in Google, Bing, and Yahoo. When I check my ranks I am not using a proxy, which should rule out SERPs changing as a result of localization. What I'm seeing is my keyword rank in the 30s across all 3 search engines, then if I check it an hour later it has completely fallen off the top 100. An hour or two later it will return somewhere in the 30s again. The site is only getting updated about once every 2 days, so I wouldn't expect that anything I am doing onsite is shifting the positions. I put a freeze on backlinking for a couple days just to see if that made a difference and I still get the same results. Is this normal behavior? I've read a lot of threads on similar topics but I haven't heard anything about positions changing on an hourly basis.