To fix the errors, try the following:
Start by restarting the PC if it's only one system or rebooting the server if this is a viable option to clear out any temporary network glitches.
If the program has crashed and is not responding, you may need to end the task via Task Manager.
If all users are getting Cannot Read Clients.XX error, please ensure all users are closed out/signed out, and then one person re-enters to see if this resolves the issue. It could mean one user has locked onto the file and has tried to make a change to the client reference code.