From previous threads this appears to be an issue with mod_security. This will be fixed in v1.7 but if you want you can fix it yourself quite easily.
Open qa-include/qa-install.php and look around line 216 for these two lines:
$buttons = array('create' => 'Create Database');
and
$buttons = array('create' => 'Create Database including User Management');
Replace them with this:
$buttons = array('create' => 'Create the Database');
and
$buttons = array('create' => 'Create the Database including User Management');