Hi,
What is the make and model of the Television?
This issue might occur if the display settings are not configured correctly. I would suggest you to try adjusting the resolution and check if it helps:
Change your screen resolution
http://windows.microsoft.com/en-US/windows7/Change-your-screen-resolution
If the issue is not resolved, I would suggest you to check if there are any settings to adjust the display manually on the Television.
Let us know if you need more assistance.