DATABASE ERROR: CONNECTION FAILED!

Unable to connect to the database!
Please contact your server-administrator.
日志：
[Mon Jun 07 09:50:36 2010] [error] [client 192.168.0.162] MDB2 Error: not found (-4): no RDBMS driver specified
[Mon Jun 07 09:50:36 2010] [error] [client 192.168.0.162] PHP Warning:  Error writing to log file logs/errors; Please check permissions in /var/www/roundcubemail-0.3.1/program/include/main.inc on line 1053
[Mon Jun 07 09:50:36 2010] [error] [client 192.168.0.162] PHP Notice:  no RDBMS driver specified in /var/www/roundcubemail-0.3.1/program/include/bugs.inc on line 86
[Mon Jun 07 09:50:36 2010] [error] [client 192.168.0.162] File does not exist: /var/www/html/.css, referer: http://mail.sskil.com/mail/
[Mon Jun 07 10:03:57 2010] [notice] caught SIGTERM, shutting down
[Mon Jun 07 10:03:58 2010] [notice] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)
[Mon Jun 07 10:03:58 2010] [notice] Digest: generating secret for digest authentication ...
[Mon Jun 07 10:03:58 2010] [notice] Digest: done
[Mon Jun 07 10:03:58 2010] [notice] Apache configured -- resuming normal operations
[Mon Jun 07 10:04:03 2010] [error] [client 192.168.0.162] File does not exist: /var/www/html/.css, referer: http://mail.sskil.com/mail/

原先是提示一个参数设置的问题，我重新配置了一下参数，现在是这个问题了，实在不知道怎么修改，还是请大家帮助一下吧，谢谢！！