What you are experiencing is the NORMAL behavior with explorer.exe.

Running Explorer.exe launches the Windows Taskbar, by default. It is a standard Windows behavior.

You have two solutions to prevent the launch of the Taskbar:

- publish explorer.exe and add in the 'parameter' field a path. 
It will open explorer with a parameter and it won't launch the Taskbar. 
- publish folder.exe (tsplus/userdesktop/files/) with our without a path in the parameters. 
By default folder.exe will display the content of the Dektop.

This screenshot shows how you can set a path, for a better understanding: