Unfortunately this post isn't about something as concrete as a bug, but it's been driving me nuts. I recently updated my blog's theme and software (I basically rewrote it) from http://old.korokithakis.net/ to http://www.korokithakis.net/.
Yesterday, I noticed all my pages dropping from Google's search results. My Python tutorial used to be 3rd for "learn python" and now it's 30th, if it even appears on the list.
I've allowed robots, all the header tags are in place, titles are the same as they used to be and the URLs that changed have permanent redirects to the new ones (the tutorial URLs haven't changed).
Still, all my pages dropped from the results. What can be having such a huge impact on the rankings?