So, if you regularly close and re-open MC, and want MC to always start up and then detach a display, you'll want to write/use a script to launch MC instead of launching it directly. Here's a script you can use for this:
<package>
<job id="vbs">
<script language="VBScript">
'Create our handy dandy Shell object
set WshShell = WScript.CreateObject("WScript.Shell")
'Start MC
WshShell.Run "mc18.exe"
'Pause for a bit
WScript.Sleep 1000
'Detach display on Zone 1
WshShell.Run "mc18.exe /MCC 10037, 1:0"
</script>
</job>
</package>
Copy and paste that text above into a blank Notepad document. Then, save it somewhere to disk as a WSF file (change the file extension to .wsf). Now, when you run the script, it will launch MC (if it isn't already running) and then a second later, it will detach the display on Zone 1. If you want to detach the display for a different Zone, just change the 1:0 part of the script above (1:0 corresponds to the first zone, 1:1 to the second, 1:2 to the third and so on and so forth).
Then, you can just change your shortcuts (in the Start Menu, Taskbar, etc) to point to this script file instead of directly to MC itself, and when you launch MC, it will always open up and then detach the selected display.