Endless shuffling of Google results
It appears lately that the shuffling of results from Google is constant. Rankings are less stable than in the past.
The mantra these days is to get links from “diverse ip sources”. A few years back, the idea was to get links from sites that have high PageRank. The theories keep changing as the results keep changing and Google has realized that it’s much tougher to hit a moving target.
Now more than ever, the best thing most webmasters can do is make sure that their site is a high-quality resource, and do not get too focused on one search engine, and what they “want” from your site. Always build your websites for the users (while being search-engine friendly of course).