Sorry, I seem to have posted on the wrong issue. Restarting the FM server app got rid of the problem of users getting kicked off, but the warning 661 issue is still there. It looks like the issue is related to the starter DB.
Good topic. I am getting a lot of these. In our situation the server uses Filemaker Accounts only to authenticate, clients use opener DB's and complain about getting kicked off a couple of times a day. Every time this happens the log generates the Warning 661, with Admin, Guest and correct username interspersed. Log entries appear every 5 to 8 minutes apart. Users experience no problems with the opener DB's, though! Server has no idle time set. Is there a solution?