Hi Linda,
Thanks for reaching out to us.
Most of the cases where we see whitescreen either there is a Memory problem (which you seem to have tested), or it’s a PHP error that is crashing your WordPress.
To allow you to see which error might be happening you will need to use the WP_DEBUG constant as pointed in the WordPress Codex page for Debugging.
If nothing pops up you can fall back to try the things pointed out on our testing for Conflicts tutorial.
I hope I was able to help you solve the issue with those two articles, if not, please don’t hesitate to reply.
My Best Regards,