[turba] Warning messages

[Haaino]

Hi,

Does anybody know what these warning messages mean? And what I should do 
to get rid of them?
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Warning: Cannot modify header information - headers already sent by 
(output started at /var/www/html/horde/turba/lib/Driver/sql.php:333) in 
/var/www/html/horde/kronolith/templates/common-header.inc on line 3

Warning: Cannot modify header information - headers already sent by 
(output started at /var/www/html/horde/turba/lib/Driver/sql.php:333) in 
/var/www/html/horde/kronolith/templates/common-header.inc on line 4
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Best regards,
Haaino