Same thing here. Installed new today. Went thru the Server Error and 755 resets on properties.php. Partial fix.
Upon first uploading images, can edit.
Upon return, Your gallery has no images. I can see a preview if I select a gallery and "choose design" the preview is ok.
Back to gallery, edit images, no joy.
Using the "add to site" and Use this URL when linking to your PowerGallery from any web page: The requested URL /PG200/galleries/6/index.php was not found on this server.
So somethin' wrong. :-)