Hi Ron,
Yes, it's a bit hard to identify the problem. I'm not teaching students, but we got staff sent us this complaints. I tried to collect information from users and see if it's browser or devices problems. I saw one "Session ID not set" error today of a colleague's. He logged on and do nothing on XOT. He talked with us in less than 15 minutes and then he chose an object and clicked on edit button and the error message returned. He had to logged out and logged on again. He was using Google Chrome v.40 and MacBook Air OS10.9.5.