Hi David,
From the information you've provided I cant see any obvious problems with what you are doing to close the idde. What happens after issuing the "idde.Quit" command if you leave it a while, does it eventually close?
Can you check that you only have one "idde.exe" process running before issuing the "idde.Quit" command. Also, what happens when you close out the idde by selecting 'Exit' from the File menu? Does it still take a while to close down? I assume that you need to quit the idde each time you need to switch between sessions?
Lastly, if you are using a Windows 7 machine can I ask you to take a look at this FAQ: FAQ: Advantages of using 'Run as Administrator' on Windows 7 for VisualDSP++. I would be interested to know if you still encounter the same behaviour after starting the idde using 'Run as Administrator'.
Regards,
Colin.