If such moments happen, you should change your password immediately, because besides the fact that there is some kind of failure, there may be a possibility that someone else is trying to access your platform in parallel. On top of that there are really weak, I would even say outdated platforms that just don't pull when you use them from two different devices at the same time or one after the other. If you come across that a lot, you should think about changing your broker. If we are talking about browser terminals, then you should check your browser. It may be a cookie, which should be cleaned periodically, they significantly slow down the work with sites, and even more so with trading terminals, but it is not difficult, now many cookies are coped with even by antivirus programs.