If you fail to log out or are unceremoniously evicted from Nexus in the middle of a session, you will likely get an error that states you are already have an active session and cannot open another. The issue will only affect the version you were in at the time. (i.e. Live or Train) 

This is a security feature of the system not not something we can change. Also, since we are a hosted client, I don't have server access to reset this for you. As some of you have already found, the session should time out in 30 minutes with no activity.

If you are locked out, the quickest solution is to stop trying to log back in and go find something else to do for 30 minutes.If after 30 minutes the session doesn't unlock itself, get in touch with me or Chris and we can get support involved.