After Windows XP, I always use the trick below to start batch files minimized with Windows Task Manager.
From http://www.pcreview.co.uk/forums/running-bat-files-minimize
Another possibility: a small freeware program named CMDH, that simply runs the requested orders in background. For example:
cmdh MyScript.cmd
No need to add "exit" to the script. Tested working in Windows XP SP3, and there is no reason it should fail on Windows 8.