No idea. Try this. Start the TD and then open up the Task Manager (Ctrl+Alt+Del, or right-click on the taskbar). Look for the TD in the process list. You won't see it on the Applications tab of the Task Manager even when it is running, but you should see the process "mshta.exe" on the Processes tab. That's the TD process. Now exit the TD and see if this process goes away. If it does not, it may be what's keeping your PC from shutting down (I don't know why). You can right-click on the process and "end" it. After the "mshta.exe" process goes away, shut down your PC and see what happens.
If the TD process DID go away when you exited the TD (and you didn't have to "end" the process) and your computer still hangs on shutdown, it's probably something else and coincidental.