The related service running on the server has failed.
The error that the customer received means that one of the Windows Services in the operating system of the appliance has failed. If this is the first time they have received this error and the appliance is functioning normally otherwise, a reboot should solve the issue.
If they have received this error multiple times or if the appliance is having other problems as well, then further investigation into the source of the problem may be required.
Please open a support case and attach a screen shot of the System Status page for this appliance and also an export of the Alerts Log filtered for All Dates. Both of these items can be found in the /paradmin interface.