Ständig Fehler: Headers allready sent

[larsu]

Hi, wenn ich in meinem forum im acp an den foren etwas bearbeite, kommt immer nach der grünen meldung die immer erscheint eine weisse seite mit folgendem fehler:

[phpBB Debug] PHP Notice: in file /includes/auth.php on line 418: Undefined variable: user_id
[phpBB Debug] PHP Notice: in file /adm/index.php on line 150: Cannot modify header information - headers already sent by (output started at /includes/functions.php:3153)
[phpBB Debug] PHP Notice: in file /adm/index.php on line 152: Cannot modify header information - headers already sent by (output started at /includes/functions.php:3153)
[phpBB Debug] PHP Notice: in file /adm/index.php on line 153: Cannot modify header information - headers already sent by (output started at /includes/functions.php:3153)
[phpBB Debug] PHP Notice: in file /adm/index.php on line 154: Cannot modify header information - headers already sent by (output started at /includes/functions.php:3153)

Diesen fehler erhalte ich auch übrigens manchmal im forum durch den debugger, komischerweise ist die schrift im forum dann immer total riesig...

Und folgenden fehler erhalte ich wenn ich den ajax chat betreten will:

started at /includes/functions.php:3153)
[phpBB Debug] PHP Notice: in file /chat/lib/class/AJAXChatHTTPHeader.php on line 41: Cannot modify header information - headers already sent by (output started at /includes/functions.php:3153)
[phpBB Debug] PHP Notice: in file /chat/lib/class/AJAXChatHTTPHeader.php on line 45: Cannot modify header information - headers already sent by (output started at /includes/functions.php:3153)