You probably need to change the refresh rate to suit your TV. Most TVs will only support a refresh rate of 50 or 60 Hz.
Also, you need to change the resolution to match the native resolution of the TV (Most TVs only support much lower resolutions than monitor screens).
Both the refresh rate and the resolution will be in the Specifications section of the TV Manual.
To change these settings:
Right-click a clear area of the desktop and choose Properties.
Click the Settings tab, and set the resolution
Click the Advanced button
Click the Monitor tab
Set the Refresh rate.
Click OK, then OK again