This problem I had during magento community installation process on localhost. I have used EasyPHP5.2.10 and after the installation of magento with the downloader I was not able to login in the backend.

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After a research on internet I have seen many posts talking about languages session problem.  So  I noticed that if you try to change language in the installation problem it reload the page on the default EN-US.

So I managed the problem by going in the apache server config file changing  “localhost:80 “to ““. After that I have installed magento again at uri In this way when I have chosen English to Italian language it worked! Than I was able to join my magento backend.