I have a client who uses Quickbooks Desktop 2019 that is installed on a Microsoft 2016 Server Standard machine. On several occasions, almost weekly, users cannot login while others are. So the system is in multi-user mode for sure but it's like it gets into this state where it thinks you are trying to login under single user mode. However if I login to the desktop of the server, sign into Quickbooks as the main admin account, then all of a sudden the users can log back in. Any ideas why this is?