Just solved this problem.
I've instaled magento in my local computer and I can't login to the admin panel.
Understanding the problem
Magento doesn't work well with 'localhost' and '127.0.0.1'. After some readings on the net I understood that these addresses won't allow cookies, resolting in admin panel login failure.
Edit 'host' file located at 'C:\Windows\System32\drivers\etc'.
Add a new line, for example:
127.0.0.1 shloemi.com # Localhost virtual development site.
You can now acces magento admin pannel using the site shloemi.com.