Upload causing internal server error

I just purchased this theme and was excited to use it for my photography. When I did the install, I get a nasty little INTERNAL SERVER ERROR message. I have followed the steps both via the zip upload and then the removal of all uploaded files (both the main and the child theme) and the FTP upload with the same result. I have never had issues with uploading themes before, so I am not sure exactly what is causing the problem. PLEASE HELP…because well $60.00 is a lot of money for a theme I won’t be able to use. I really hope you can assist with this problem cause this theme demo looks perfect for what I need.

Regards,
Mitzi