Warning: Cannot modify header information .. and all that

Hello all,

I get the dreaded “Warning: Cannot modify header information – headers already sent by (output started at /home/content/67/xxxxxx/html/index.php:1) in /home/content/67/xxxxxx/html/wp-includes/pluggable.php on line 881” message on my website.

On Line 881 of pluggable.php the code reads as follows:
————————————————–
if ( !function_exists(‘check_admin_referer’) ) :
/**
* Makes sure that a user was referred from another admin page.
*
* To avoid security exploits.
*
* @since 1.2.0
* @uses do_action() Calls ‘check_admin_referer’ on $action.
*
* @param string $action Action nonce
* @param string $query_arg where to look for nonce in $_REQUEST (since 2.5)
*/
function check_admin_referer($action = -1, $query_arg = ‘_wpnonce’) {
if ( -1 == $action )
THIS IS LINE 881 _doing_it_wrong( __FUNCTION__, __( ‘You should specify a nonce action to be verified by using the first parameter.’ ), ‘3.2’ );
—————————————-
Any suggestions how I can fix this?

Thank you in advance.

Uttam