If she sent you the actual saved ProShow Slideshow file (but not ran through the output process), and the PXC file that accompanies it, you should be able to edit the show. But, if she only sent you the created output (finished show), then you probably can not edit anything. I am not sure about compatibility across different version of ProShow, but if you have the same version, you should be able to edit the original unprocessed file.
Thanks. What I have is the finished output DVD. That's why I could not edit the files then.