1) what version of Atahualpa?
2) Have you made any changes to the theme code?
3) when you change 'ATO->Header Image->Header Image: Height' to 250 and hit save, if you go to another dashboard setting - like users - then back to 'ATO->Header Image', does the new value you entered still show or is it back to the default 250?
4) who is your host
5) do you know what version of php you are running? If not go to ATO->Style & edit CENTER COLUMN->Content ABOVE the LOOP and add the following as the first line
HTML Code:
<?php global $user_ID; if( $user_ID ) { if( current_user_can('level_10') ) { phpinfo(); } }; ?>
this will cause the display only to show up when you are logged in as an admin. Once you look at your home page you should see a dump of the php info and can get the version from it. Then you can remove that line of code.
6) If on 3.4.9 or newer, export your settings and attach them here (use the paper clip icon)