The problem is your server will not allow PHP files to be executed if they are 'writable by group'. This means you PHP files need to be CHMOD'd to remove this permission.
You will need to CHMOD these files to 644:
/index.php
/js.php
/styles.php
/admin/index.php
/lib/tiny_mce/tiny_mce.php
/lib/tiny_mce/tiny_mce_gzip.php
/lib/iepngfix_v2/iepngfix.php
And these directories to 755:
/admin/
/lib/
/lib/tiny_mce/
/lib/iepngfix_v2/

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