When you want to schedule a report in client mode using C1ReportScheduler you may get an an error saying the xml is not found. The problem is because the xml file is accessed from the mapped drive. The Standalone mode is able to run successfully because Standalone mode has the local user account used by the 'C1ReportsScheduler' service which can easily access the network locations. But, when the mode is switched to client mode, the network locations are not accessed because the service account that used to access the file might not have the right to access the network location. Therefore, in order to remove the problem you need to do the following:
The error should not occur after this. If in case you still face the problem, contact our Support team at our forums.