.htaccess issue - Please Help

[eluser]Blues Clues[/eluser]
I have the following .htaccess file in my installation and still not able to eliminate index.php in my links...


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.htaccess settings
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RewriteEngine on
RewriteCond $1 !^(index\.php|images|css|js|robots\.txt|favicon\.ico)
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([^/\.]*)$ ./index.php/$1 [QSA]
RewriteRule ^(.*)$ ./index.php/$1 [QSA]
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config.php settings:
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$config['base_url'] = "http://localhost/codeigniter172/";
$config['index_page'] = "";

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Problem: I am still not able eliminate index.php in my URLs...For example:

http://localhost/codeigniter172/index.php/mainp/ loads my menu

but

http://localhost/codeigniter172/mainp/ fails with HTTP 404 error.

Can somebody help with this?