An error occurred when loading the system Windows PowerShell Snap-Ins.

I have a wcf service. And I am running some cmdlets as below

Runspace runspace = RunspaceFactory.CreateRunspace();

                    // open it
                    runspace.Open();

                    Pipeline pipeline = runspace.CreatePipeline();
                    RunspaceInvoke scriptInvoker = new RunspaceInvoke(runspace);

                    Command myCommand = new Command("Import-Module");
                    myCommand.Parameters.Add("Name", "virtualmachinemanager");

........

I have hosted this service on a machine with credentials MYDOM/user1. And from here It runs. but when I Call this service with other credentials say MYDOM/Administrator it gives error message "An error occurred when loading the system Windows PowerShell Snap-Ins. Please contact Microsoft Support Services."