Problems uploaden pictures

Hi, after moving my wordpress weblog from one hosting provider to another i´m not able to upload files from the write post function. I get the following error:

The uploaded file could not be moved to /var/www/vhosts/familiekoning.com/subdomains/patrick/httpdocs/wp-content/uploads/2007/09.
Warning: Cannot modify header information – headers already sent by (output started at /var/www/vhosts/familiekoning.com/subdomains/patrick/httpdocs/wp-admin/admin-functions.php:1986) in /var/www/vhosts/familiekoning.com/subdomains/patrick/httpdocs/wp-includes/functions.php on line 1357

I read a lot about deleting spaces after the php start and end tag, disabled all my plugins, but nothing works.

Who can help me?

Thanks, Patrick