I was having the same problem when I was trying to login to the backend. Magento kept redirecting me to the login page without any warnings whatsoever.
I added a new entry on my local hosts file (c:\windows\system32\drivers\etc) like this:
127.0.0.1 localhost.com
and I installed magento again using localhost.com/magento from the beggining. That solved my redirecting problem.