This message indicates that the server or terminal server the user is connecting through, has undergone a backup or snapshot while users were logged into FIMS.  The server will need to be rebooted before users are able to use FIMS.

See this progress solution article for more details.

If a nightly backup is causing this problem, one suggestion is to create a scheduled task on the FIMS server, which stops the databases in the evening, and turns them back on after the backup/snapshot is complete.