[Zen Cart] Get blank page on product info

[analex12]

I am only using the product info page and following functions in Zencart. When I access the product info page I receive a blank screen. I had MSU working at one point. The issue I had at that time was Zencart would only add 1 Item to the add to cart page. The url of the product info page was shortened properly. The add to cart page url had the dynamic url information in it. I tried to load the original zencart files into a later version & that is when I receive a blank product info page. I also tried to run the activation function & that page came up blank. Trying to create a new htaccess file also did not work. When I disable the MSU function the product info page works properly as well as the add to cart function ( adding multiple products). Msu is installed in the following site: http://www.anthonysbabyboutique.com/Zencart/

[inveo]

We have checked your site and there is HTTP 500 Internal Server Error page. It means there is something wrong with your PHP or Apache installation. Please make sure you are using the latest PHP version with no 3rd party patches