Hi Barbara, It definitely sounds like a network connection issue for both problems. The blank screen or error message is likely the result of the browser "timing out". We have these issues on occasion too with pages that are high on media using a Wifi, but so long as the connection hasn't dropped, they can usually try again and it will work. (A dropped connection is another thing.)
Have you tried plugging the laptops & desktops into a network drop to see if the same errors occur? Have you spoken to your university network specialists? My suspicion is that it may be a wifi strength issue.