hb-maintenance.php

I’m having the exact same issue as a previous poster, so I will copy/paste his message:

I am having a problem with:
“cannot modify header information – headers already sent by (output started at /home….)
../wp-content/themes/Highend/hb-maintenance.php on line 11, 12 and 13

On an “under construction” page

I’m pretty new with wordpress, so pardon my ignorance.

I’ve disabled all plugins as suggested in that thread, but it’s no help. Thanks.