[Plugin ecommerce Gold Cart] Upload upgrade files and site crashes

I recently purchased the Gold Cart upgrade and followed all the instructions on where to upload the files to and when i do it crashes my site. At first it wouldnt allow me to upload the files to the /public_html/wp-content/uploads/wpsc/upgrades/ folder but that was to do with the permissions and i contacted my web hosting company and they fixed that issue.

However when it allowed me to upload the files it seemed ok to begin with and allowed me to enter my username and API key and said id successfully upgraded the Plugin. However when the page refreshed i was left with a white page and nothing more. I had to remove the Gold Cart files and then the site worked again. Now everytime ive tried to reupload the Gold Cart files to upgrade again i get presented with the same white screen.