The DLL file is used by the software and it's a control library. I believe there is something wrong with the installation itself, because the file should be provided along with the setup package.
Since the file is not officially available, you will need to perform a Google Search for the DLL. Download the DLL file and copy it in the installation folder or to Windows installation directory under System32.
Open Start > Run > type "regsvr32 pctree32.dll" and then try to run the main product again.