Keep useres logged in...

Drupal uses php sessions. 4.5 puts the session settings in the .htaccess file which does not work on all web servers depending on the server's configuration. I use 1and1.com as my hosting company and they do no support php settings in the .htaccess file. If your host does not support this you can duplicate the configuration in version 4.6. Copy the following code into your includes/conf.php file or sitename.php if you have multiple site configuration setup.

/**
 * PHP settings:
 *
 * To see what PHP settings are possible, including whether they can
 * be set at runtime (ie., when ini_set() occurs), read the PHP
 * documentation at http://www.php.net/manual/en/ini.php#ini.list
 * and take a look at the .htaccess file to see which non-runtime
 * settings are used there. Settings defined here should not be
 * duplicated there so as to avoid conflict issues.
 */
ini_set('arg_separator.output',     '&');
ini_set('magic_quotes_runtime',     0);
ini_set('magic_quotes_sybase',      0);
ini_set('session.cache_expire',     200000);
ini_set('session.cache_limiter',    'none');
ini_set('session.cookie_lifetime',  2000000);
ini_set('session.gc_maxlifetime',   200000);
ini_set('session.save_handler',     'user');
ini_set('session.use_only_cookies', 1);
ini_set('session.use_trans_sid',    0);

Make sure you remove these php settings in your .htaccess file (this is a hidden file in your drupal root directory.)

Another more difficult way to do this is to put a php.ini file in each subdirectory of your drupal site that has files ending in php. You can put the file in your drupal root, then create a link to each of the subdirectories. But this is messy.