Julie you must be running phpBB 2.018 or above. phpBB changed there authentication and we updated our integration to account for this.
Upgrading phpbb is a snap. Just upload all the phpbb files except config.php. You might want to make a backup of yor old overall_header.tpl file in your templates style directory if you have like a real modified header. Upload all files and run
http://www.domain.com/phpbb/install/..._to_latest.php
thats it. Then remove the install and contrib directories