Look in device manager to see if there is a Yellow exclamation mark against Teredo Tunneling Pseudo-Interface
You can try updating your network driver by following these steps:
* Right click the Teredo Tunneling Pseudo-Interface
* Update Driver Software...
* Browse my computer for driver software
* Let me pick from a list of device drivers on my computer
* Select from the list and update the driver.
Also you may get this mark because the network adapter may not be compatible with Windows 7. Request you to contact the manufacturer’s website and download the latest driver/adaptor that is compatible with Windows 7.
To check for compatibility in windows 7, visit the below mentioned link:
This link from Technet talks about other ways to fix the problem.