Hi WT,
I was having the same issue. I ended up writing a VBS that hides the command window, and calling that VBS from the command line in the SyncToyCmd scheduled task:
Command line in the scheduled task: "C:\Program Files\SyncToy 2.1\scheduledBackup.vbs"
Contents of "scheduledBackup.vbs":
const HIDDEN_WINDOW = 12
strComputer = "."
Set objWMIService = GetObject("winmgmts:" _
& "{impersonationLevel=impersonate}!\\" & strComputer & "\root\cimv2")
Set objStartup = objWMIService.Get("Win32_ProcessStartup")
Set objConfig = objStartup.SpawnInstance_
objConfig.ShowWindow = HIDDEN_WINDOW
Set objProcess = GetObject("winmgmts:root\cimv2:Win32_Process")
errReturn = objProcess.Create("C:\Program Files\SyncToy 2.1\SyncToyCmd.exe -R", null, objConfig, intProcessID)
Works like a charm so far.
Sources:
http://www.geekstogo.com/forum/Hide-command-prompt-windows-t56092.html
http://msdn.microsoft.com/en-us/library/aa394375%28v=VS.85%29.aspx
http://gallery.technet.microsoft.com/ScriptCenter/en-us/8bbed56f-a7aa-491f-a296-687dd96098a3
