Running OSX Lion Server (10.7.4), and about once a week or so the Apple File Sharing service stops letting clients connect to its shares. On the client we will see a dialog box stating "There was a problem connecting to the server ". Browsing the server we simply no longer see the shares. The clients are also running the latest OSX (10.7.4)

In /var/log/system.log we see entries like the following:

Jun 26 08:38:22 w3 AppleFileServer[20511]: received message with invalid client_id 157

Jun 26 08:42:11 w3 AppleFileServer[20511]: received message with invalid client_id 165

Jun 26 08:42:21 w3 AppleFileServer[20511]: received message with invalid client_id 174

Where 20511 appears to be the pid, and client_id appears to be incremented with each failed attempt.

Nothing jumps out at me from /Library/Logs/AppleFileService/AppleFileService[Access|Error].log

Restarting the service fixes the problem:

serveradmin stop afp && serveradmin start afp

So I added a script to do this daily using the periodic service. But, we still encounter this problem about once a a week.