I think you may have some corrupted files. The index.php file at the power gallery root should have a redirect to the admin_gallery/index.php file in.
The index file you attached here is the one that should be in the admin_gallery folder, it should not be at the root of the gallery files.
the index file at the root of the gallery should just have this code in it:
try downloading a fresh copy of the power gallery files from the download center.