live site down because session files are not deleted by php4 HELP

Hi, We have a site that goes down because of the php 4 sessions: PHP saves session files on the server in the same directory as mySQL and therefore there is not enough swap space in that directory for mySQL to work so it goes down, BECAUSE The session files from php don't get deleted?? Question: How can we make PHP delete old sessions? I figure it's a setting in php setup? More info: From the phpinfo: session.auto_start Off Off session.cache_expire 180 180 session.cache_limiter nocache nocache session.cookie_domain no value no value session.cookie_lifetime 43200 43200 session.cookie_path / / session.entropy_file no value no value session.entropy_length 0 0 session.gc_maxlifetime 1440 1440 session.gc_probability 1 1 session.name SESSID SESSID session.referer_check no value no value session.save_handler files files session.save_path /tmp /tmp session.serialize_handler php php session.use_cookies On On If anyone has any idea how to make sure the old session files get deleted by PHP can you tell us? Is it a setting in PHP setup and if so how can we easily change that? Thanks so much! Peter