session problems

Can't seem to get sessions to work in PHP4. No idea why. They work only in the specialized case where I turn on auto-start, and I access the script directly. Even with auto-start on, the session won't register if I access the script through a link from another script. Without auto-start on, it's like the session_start() function doesn't even do anything. It's very strange. I'm running PHP 4.0.3 on Solaris with Postgres. I'm including my build config and the session part of php.ini, just in case I've done something stupid. ./configure --with-apxs=/opt/apache/bin/apxs \ --without-mysql \ --enable-ftp \ --with-gettext \ --enable-sysvsem \ --enable-sysvshm \ --with-dbase=yes \ --enable-debug=no \ --enable-safe-mode=no \ --enable-url-fopen-wrapper=yes \ --enable-track-vars=yes \ --with-pgsql \ --enable-trans-sid=no \ --with-imap [Session] session.save_handler = files ; handler used to store/retrieve data session.save_path = /tmp ; argument passed to save_handler ; in the case of files, this is the ; path where data files are stored session.use_cookies = 1 ; whether to use cookies session.name = PHPSESSID ; name of the session ; is used as cookie name session.auto_start = 1 ; initialize session on request startup session.cookie_lifetime = 0 ; lifetime in seconds of cookie ; or if 0, until browser is restarted session.cookie_path = / ; the path the cookie is valid for session.cookie_domain = ; the domain the cookie is valid for session.serialize_handler = php ; handler used to serialize data ; php is the standard serializer of PHP session.gc_probability = 1 ; percentual probability that the ; 'garbage collection' process is started ; on every session initialization session.gc_maxlifetime = 1440 ; after this number of seconds, stored ; data will be seen as 'garbage' and ; cleaned up by the gc process session.referer_check = 1 ; check HTTP Referer to invalidate ; externally stored URLs containing ids session.entropy_length = 0 ; how many bytes to read from the file session.entropy_file = ; specified here to create the session id ; session.entropy_length = 16 ; session.entropy_file = /dev/urandom session.cache_limiter = nocache ; set to {nocache,private,public} to ; determine HTTP caching aspects session.cache_expire = 180 ; document expires after n minutes