I believe at least part of the 'white screen' problem is a failre to handle product references properly. Every time I have had the white screen I have gone back to the input page and see that the product reference links are changed to 'undefined'. Every time it has failed one of the references has been to a product by Danie who has a long list of products. And guess what, Sveva has a long list of products. This strongly indicates a bug in the code to find the product thumbnail that fails when the list for that vendor is too long. Very common type of software bug. Very amateurish not to trap it with an error message.