This is caused by an issue with the USB 3.0 driver in Windows 8. To rectify the problem, open the Virtual Machine Settings and select the USB controller. Change the USB compatibility to "USB 2.0". Once this setting has been changed, make sure that you have connected the USB licence dongle to the Virtual Machine and then launch NetAnalysis® / HstEx®.
If you are running NetAnalysis®, HstEx® or Blade® in evaluation mode, you will not be able to use a virtual environment. This functionality is only available in the full licensed software and has been disabled for virtual environments.