Warning: The Virtual Directory tool is an advanced tool.
Improper use of this tool can render your website nonfunctional.
The Virtual Directory tool in the control panel allows you to designate a directory as another application within IIS.
It means that you have separate Session,Application,web.config files for your Virtual Directory and you couldnt share your session between Virtual Directory and your parent web.
So You will lost all your session variables if you pass your page to the page inside the Virtual Directory.