How do I terminate DosBox after a successful "exit" ?

Command line ="C:\Program Files\DOSBox-0.72\dosbox.exe" c:\oldmahj -exit -c mahjongg -fullscreen -noconsole

System:
WinXP Pro V2002 sp3
Intel Pentium 4 @ 2.4Ghz
2GB RAM

If I run this command more than three times, DosBox fails to initiate and I must use taskmanager to terminate 3 DosBox Administrator processes that are still actively occupying memory (yuck!)
I think they should terminate coincident with a successful -exit execution...don't you?