If the QBCFMonitorServer stops, users are unable to log into Quickbooks.
You may see this event in the Application event log:
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
The easiest fix for the issue is to set the QBCFMonitorService to automatically restart after failure.
To do this, go to services and find the QBCFMonitorService.
Open up the properties for the service and go to the Recovery Tab, change the setting on the Tab to restart the service for first, second, and subsequent failures.
If you want to prevent the service from crashing you will have to disable Quickbooks Auto Data Recovery feature (not recommended).
To disable ADR you have to find the qbw.ini file in C:ProgramDataIntuitQuickBooks Enterprise Solutions 13.0.
In that file you will find 2 lines for ADR, change the 2nd line QBAUTOBACKUP from 1 to 0.
Then for best result restart the computer.
Please note, this disables data recovery features that could be helpful in situations where data loss occurs.
For more details on ADR and what it does visit this link: http://support.quickbooks.intuit.com/support/articles/HOW13772