categories and posts don’t update

I have this problem:

You have an error in your SQL syntax….

Warning: Cannot modify header information – headers already sent by (output started at /web/htdocs/…/home/wp-includes/wp-db.php:98) in /web/htdocs/…/home/wp-admin/post.php on line 397

Warning: Invalid argument supplied for foreach() in /web/htdocs/…/home/wp-admin/post.php on line 419

Warning: Invalid argument supplied for foreach() in /web/htdocs/…/home/wp-admin/post.php on line 425

I can’t modify posts, categories don’t update (turn into uncategorized).