fresh install D 7_12 recognizes that a site is allready installed [gohst installation by whom !?] bug or feature

well believe it or not. just did a fresh install with d 7-12 [released on 2012 feb. 01]

first of all - i am strugling with t he htaccess for months not. with the orignial htaccess i have no luck at all. With that - all i get is the following

Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, webmaster@boysday.org and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.

okay - for several months i do the following; i exchange the htaccess-file with the following one:
that is overworked by my serveradmin http://pastebin.de/22149
See this links and make up your mind - about this courious error.

Well but with this alone i get a blank site

Next-step: trying out a settings-file - that is derived from a drupal commons 6.x24 - [very very curiouls and strange - i know - but what should i do] When i upload a settings-file that is derived from the default.settings.php then i alos get a blank page If i upload a settings file (/that i have taken from the drupal commons 6x-24 - which is obviousliy blank (not filled in with something) then i get the following

Drupal already installed

To start over, you must empty your existing database.
To install to a different database, edit the appropriate settings.php file in the sites folder.
To upgrade an existing installation, proceed to the update script.
View your existing site.

Well here you have a quick overview on the settings-file that i use: that is derived from a drupal commons 6.x24 -

look forward to hear from you

greetings unleash

<?php

/**
 * @file
 * Drupal site-specific configuration file.
 *
 * IMPORTANT NOTE:
 * This file may have been set to read-only by the Drupal installation
 * program. If you make changes to this file, be sure to protect it again
 * after making your modifications. Failure to remove write permissions
 * to this file is a security risk.
 *
 * The configuration file to be loaded is based upon the rules below.
 *
 * The configuration directory will be discovered by stripping the
 * website's hostname from left to right and pathname from right to
 * left. The first configuration file found will be used and any
 * others will be ignored. If no other configuration file is found
 * then the default configuration file at 'sites/default' will be used.
 *
 * For example, for a fictitious site installed at
 * http://www.drupal.org/mysite/test/, the 'settings.php'
 * is searched in the following directories:
 *
 *  1. sites/www.drupal.org.mysite.test
 *  2. sites/drupal.org.mysite.test
 *  3. sites/org.mysite.test
 *
 *  4. sites/www.drupal.org.mysite
 *  5. sites/drupal.org.mysite
 *  6. sites/org.mysite
 *
 *  7. sites/www.drupal.org
 *  8. sites/drupal.org
 *  9. sites/org
 *
 * 10. sites/default
 *
 * If you are installing on a non-standard port number, prefix the
 * hostname with that number. For example,
 * http://www.drupal.org:8080/mysite/test/ could be loaded from
 * sites/8080.www.drupal.org.mysite.test/.
 */

/**
 * Database settings:
 *
 * Note that the $db_url variable gets parsed using PHP's built-in
 * URL parser (i.e. using the "parse_url()" function) so make sure
 * not to confuse the parser. If your username, password
 * or database name contain characters used to delineate
 * $db_url parts, you can escape them via URI hex encodings:
 *
 *   : = %3a   / = %2f   @ = %40
 *   + = %2b   ( = %28   ) = %29
 *   ? = %3f   = = %3d   & = %26
 *
 * To specify multiple connections to be used in your site (i.e. for
 * complex custom modules) you can also specify an associative array
 * of $db_url variables with the 'default' element used until otherwise
 * requested.
 *
 * You can optionally set prefixes for some or all database table names
 * by using the $db_prefix setting. If a prefix is specified, the table
 * name will be prepended with its value. Be sure to use valid database
 * characters only, usually alphanumeric and underscore. If no prefixes
 * are desired, leave it as an empty string ''.
 *
 * To have all database names prefixed, set $db_prefix as a string:
 *
 *   $db_prefix = 'main_';
 *
 * To provide prefixes for specific tables, set $db_prefix as an array.
 * The array's keys are the table names and the values are the prefixes.
 * The 'default' element holds the prefix for any tables not specified
 * elsewhere in the array. Example:
 *
 *   $db_prefix = array(
 *     'default'   => 'main_',
 *     'users'     => 'shared_',
 *     'sessions'  => 'shared_',
 *     'role'      => 'shared_',
 *     'authmap'   => 'shared_',
 *   );
 *
 * Database URL format:
 *   $db_url = 'mysql://username:password@localhost/databasename';
 *   $db_url = 'mysqli://username:password@localhost/databasename';
 *   $db_url = 'pgsql://username:password@localhost/databasename';
 */
$db_url = 'mysql://username:password@localhost/databasename';
$db_prefix = '';

/**
 * Database default collation.
 *
 * All data stored in Drupal is in UTF-8. Certain databases, such as MySQL,
 * support different algorithms for comparing, indexing, and sorting characters;
 * a so called "collation". The default collation of a database normally works
 * for many use-cases, but depending on the language(s) of the stored data, it
 * may be necessary to use a different collation.
 * Important:
 * - Only set or change this value BEFORE installing Drupal, unless you know
 *   what you are doing.
 * - All database tables and columns should be in the same collation. Otherwise,
 *   string comparisons performed for table JOINs will be significantly slower.
 * - Especially when storing data in German or Russian on MySQL 5.1+, you want
 *   to use the 'utf8_unicode_ci' collation instead.
 *
 * @see http://drupal.org/node/772678
 */
# $db_collation = 'utf8_general_ci';

/**
 * Access control for update.php script
 *
 * If you are updating your Drupal installation using the update.php script
 * being not logged in as administrator, you will need to modify the access
 * check statement below. Change the FALSE to a TRUE to disable the access
 * check. After finishing the upgrade, be sure to open this file again
 * and change the TRUE back to a FALSE!
 */
$update_free_access = FALSE;

/**
 * Base URL (optional).
 *
 * If you are experiencing issues with different site domains,
 * uncomment the Base URL statement below (remove the leading hash sign)
 * and fill in the absolute URL to your Drupal installation.
 *
 * You might also want to force users to use a given domain.
 * See the .htaccess file for more information.
 *
 * Examples:
 *   $base_url = 'http://www.example.com';
 *   $base_url = 'http://www.example.com:8888';
 *   $base_url = 'http://www.example.com/drupal';
 *   $base_url = 'https://www.example.com:8888/drupal';
 *
 * It is not allowed to have a trailing slash; Drupal will add it
 * for you.
 */
# $base_url = 'http://www.example.com';  // NO trailing slash!

/**
 * PHP settings:
 *
 * To see what PHP settings are possible, including whether they can
 * be set at runtime (ie., when ini_set() occurs), read the PHP
 * documentation at http://www.php.net/manual/en/ini.php#ini.list
 * and take a look at the .htaccess file to see which non-runtime
 * settings are used there. Settings defined here should not be
 * duplicated there so as to avoid conflict issues.
 */
ini_set('arg_separator.output',     '&amp;');
ini_set('magic_quotes_runtime',     0);
ini_set('magic_quotes_sybase',      0);
ini_set('session.cache_expire',     200000);
ini_set('session.cache_limiter',    'none');
ini_set('session.cookie_lifetime',  2000000);
ini_set('session.gc_maxlifetime',   200000);
ini_set('session.save_handler',     'user');
ini_set('session.use_cookies',      1);
ini_set('session.use_only_cookies', 1);
ini_set('session.use_trans_sid',    0);
ini_set('url_rewriter.tags',        '');

/**
 * If you encounter a situation where users post a large amount of text, and
 * the result is stripped out upon viewing but can still be edited, Drupal's
 * output filter may not have sufficient memory to process it. If you
 * experience this issue, you may wish to uncomment the following two lines
 * and increase the limits of these variables. For more information, see
 * http://php.net/manual/en/pcre.configuration.php.
 */
# ini_set('pcre.backtrack_limit', 200000);
# ini_set('pcre.recursion_limit', 200000);

/**
 * Drupal automatically generates a unique session cookie name for each site
 * based on on its full domain name. If you have multiple domains pointing at
 * the same Drupal site, you can either redirect them all to a single domain
 * (see comment in .htaccess), or uncomment the line below and specify their
 * shared base domain. Doing so assures that users remain logged in as they
 * cross between your various domains.
 */
# $cookie_domain = 'example.com';

/**
 * Variable overrides:
 *
 * To override specific entries in the 'variable' table for this site,
 * set them here. You usually don't need to use this feature. This is
 * useful in a configuration file for a vhost or directory, rather than
 * the default settings.php. Any configuration setting from the 'variable'
 * table can be given a new value. Note that any values you provide in
 * these variable overrides will not be modifiable from the Drupal
 * administration interface.
 *
 * Remove the leading hash signs to enable.
 */
# $conf = array(
#   'site_name' => 'My Drupal site',
#   'theme_default' => 'minnelli',
#   'anonymous' => 'Visitor',
/**
 * A custom theme can be set for the off-line page. This applies when the site
 * is explicitly set to off-line mode through the administration page or when
 * the database is inactive due to an error. It can be set through the
 * 'maintenance_theme' key. The template file should also be copied into the
 * theme. It is located inside 'modules/system/maintenance-page.tpl.php'.
 * Note: This setting does not apply to installation and update pages.
 */
#   'maintenance_theme' => 'minnelli',
/**
 * reverse_proxy accepts a boolean value.
 *
 * Enable this setting to determine the correct IP address of the remote
 * client by examining information stored in the X-Forwarded-For headers.
 * X-Forwarded-For headers are a standard mechanism for identifying client
 * systems connecting through a reverse proxy server, such as Squid or
 * Pound. Reverse proxy servers are often used to enhance the performance
 * of heavily visited sites and may also provide other site caching,
 * security or encryption benefits. If this Drupal installation operates
 * behind a reverse proxy, this setting should be enabled so that correct
 * IP address information is captured in Drupal's session management,
 * logging, statistics and access management systems; if you are unsure
 * about this setting, do not have a reverse proxy, or Drupal operates in
 * a shared hosting environment, this setting should be set to disabled.
 */
#   'reverse_proxy' => TRUE,
/**
 * reverse_proxy accepts an array of IP addresses.
 *
 * Each element of this array is the IP address of any of your reverse
 * proxies. Filling this array Drupal will trust the information stored
 * in the X-Forwarded-For headers only if Remote IP address is one of
 * these, that is the request reaches the web server from one of your
 * reverse proxies. Otherwise, the client could directly connect to
 * your web server spoofing the X-Forwarded-For headers.
 */
#   'reverse_proxy_addresses' => array('a.b.c.d', ...),
# );

/**
 * String overrides:
 *
 * To override specific strings on your site with or without enabling locale
 * module, add an entry to this list. This functionality allows you to change
 * a small number of your site's default English language interface strings.
 *
 * Remove the leading hash signs to enable.
 */
# $conf['locale_custom_strings_en'] = array(
#   'forum'      => 'Discussion board',
#   '@count min' => '@count minutes',
# );