[wp-testers] Error

[Frank Bueltge]

*Warning*: join() [function.join <http://bueltge.de/wp-admin/function.join>]:
Invalid arguments passed in */www/htdocs/w0079121/wp-includes/wp-db.php* on
line *972*

*Warning*: Cannot modify header information - headers already sent by
(output started at /www/htdocs/w0079121/wp-includes/wp-db.php:972) in *
/www/htdocs/w0079121/wp-includes/pluggable.php* on line *850
*

in 2.7beta 3 9889
I ahve this error in may sites, in backend and frontend