I don't know how your "daisy" theme is built, but normally, the first few lines you wrote above shouldn't be in wp-content/themes/daisy...
Are you really sure the code you pasted is in wp-content/themes/daisy ???
You have TWO index.php...
One in the root directory where you installed wordpress :
http://www.where_you_installed_wordpress/index.php
This one should contain a short and sweet code :
<?php
/* Short and sweet */
define('WP_USE_THEMES', true);
require('./wp-blog-header.php');
?>
NOTE THE : require('./wp-blog-header.php'); ... this require is really important, this is where all the core WP functions, like bloginfo, are included...
Then, you have another index.php in wp-content/themes/daisy/
Where you will likely find the first line :
<?php get_header(); ?>... the header.php you should fid in your theme directory...
It seems to me that you have an exotic configuration...
Your two next steps :
1) switch theme to the default theme and see if the problem still occur.
2) Yes, backup your wp-config.php, the /wp-content directory to save your stuff, backup your database, and follow the steps to upgrade your wordpress... At least, you will be able to troubleshoot your theme on a fresh new base...
S.