Adobe LiveCycle Workbench is in use

Whenever I starts Adobe LiveCycle Workbench ES, it always shows an error as shown in the image below. It always happen even if I just restarted my computer ensuring that I have no other application running. I want to know why this error appears and if its possible to help me resolve it. Thank you.

Workbench Error

The LiveCycle Workbench workspace is currently in use.

You must close the other instance of Workbench to proceed.