backend error

[lukoie]

i've got this eror on my /admin/ page while trying to login:
Warning: Cannot modify header information - headers already sent by (output started at /home/MYDOMAIN/admin/index.php:17) in /home/MYDOMAIN/admin/template/header.php on line 19
v3.3.0
how do i fix it?

ps: to be noted, i have a "php get_header();" tag in my template, if its the case.

[shawn_a]

Means something is throwing an error
check data/other/logs/error.txt

[lukoie]

its
[15-Jan-2014 18:50:50 Asia/Jerusalem] PHP Warning: file_get_contents(/DOMAIN/data/pages/.xml) [<a href='function.file-get-contents'>function.file-get-contents</a>]: failed to open stream: No such file or directory in /DOMAIN/admin/inc/caching_functions.php on line 91