Restart your teacher's computer.  Do the following before connecting to a Vision classroom:

 

Right-click the blue Vision icon on your desktop, go to properties.  Click advanced.  Increase the ping timeout to the maximum and click apply.  Change the IP interface to the network card you are using to connect to your clients.  Click on the extended tab.  Uncheck the last 3 checkboxes starting with ’use address cache’ and ending with ‘use internal name resolution’ then click apply.  Go to the screen capture tab and click select capture source then on the drop-down, then select the wireless screen capture driver, and click ok back to your desktop.  Restart the computer.