If you are having trouble starting the Virtual DataPort server, you can try the following:
* Make sure that the port used by the Virtual DataPort server (the default port is 9999) is not being used by any other application.
* Start a command prompt with administrator privileges, and execute the "vqlserver_startup.bat" located in the "<DENODO_HOME>/bin" folder.
In the case that the error persists, you should check the "vdp.log" file located in "<DENODO_HOME>/logs/vdp" for more details about why the error is occurring.
Hope this helps!