WordPress MU

I am posting this emergency request for assistance here AFTER doing searched here and on Google.

I logged into our site's admin page earlier today and foolishly clicked on "update." Several hours later, I am trying to login, and I am getting error messages:

Warning: Cannot modify header information - headers already sent by (output started at /home/theword/public_html/online/wp-content/themes/default/functions.php:263) in /home/theword/public_html/online/wp-login.php on line 12

Warning: Cannot modify header information - headers already sent by (output started at /home/theword/public_html/online/wp-content/themes/default/functions.php:263) in /home/theword/public_html/online/wp-includes/pluggable.php on line 376

Warning: Cannot modify header information - headers already sent by (output started at /home/theword/public_html/online/wp-content/themes/default/functions.php:263) in /home/theword/public_html/online/wp-includes/pluggable.php on line 377

Warning: Cannot modify header information - headers already sent by (output started at /home/theword/public_html/online/wp-content/themes/default/functions.php:263) in /home/theword/public_html/online/wp-includes/pluggable.php on line 338

Any suggestions as to what I can do to fix this.

OK

I checked out the line 263 in my default theme's function.php file.

It looks like this:

<?php
if ( function_exists('register_sidebar') )
register_sidebars(4);
?>

There is NO extra carriage return, no white space. Nada.

Not for any other of these files either.

Well ...

I uploaded the original version of functions.php

Works like a champ.

I have no frigging idea what I had changed in this damn thing. No doubt some plugin or something will stop working now.

Consider the thread closed.