I am running Vista Home basic system, and I play Xampp, after I have installed Magento, I found I can not login the admin panel.
I found the problem is in Session, magento can not set session and always create it again, that is why logination does not work.
-Go to app/code/core/Mage/Core/Model/Session/Abstract/Varien.php file within your magento directory.
-Find the code,
session_set_cookie_params(
$this->getCookie()->getLifetime(),
$this->getCookie()->getPath(),
$this->getCookie()->getDomain(),
$this->getCookie()->isSecure(),
$this->getCookie()->getHttponly()
);
-Replace above code by,
session_set_cookie_params(
$this->getCookie()->getLifetime(),
$this->getCookie()->getPath()
//$this->getCookie()->getDomain(),
//$this->getCookie()->isSecure(),
//$this->getCookie()->getHttponly()
);
-Save it and try to login to your magento admin panel.
if u only comment the lines instead of replacing text take a good look at commas !