login page not appearing

Problem description:
I have 4 out of 12 students in a class unable to log in as the login page is not appearing when they click the button. This is on all platforms and all browsers, cleaing caches etc not helping.

Expected behavior:
Login form opens in browser window.

Actual behavior:
Werb page is blank.

Steps to reproduce:
Individual to machines.

Bug appears at this link:

Chrome/Safari/Firefox Windows/Mac/Android