Please follow the steps below in order to rectify this issue:
1. Unplug the TV from the wall, and leave it unplugged for 15 minutes, allowing all static charge inside the unit to fully disperse.
2. Re-attach the unit to the wall socket, power the TV on and allow the TV to boot up.
3. Select the DTV input/source mode.
4. Press the 'MENU' button on your remote.
5. Scroll through the menu to the 'Time' section.
6. Select the 'Auto Standby' option and press 'OK'.
7. Select "OFF" from the options and press 'OK.
Once you have followed the steps above, please close the TV's menu, and your issue will be rectified.
Please resume normal DTV playback for a fair duration of time to ensure the issue has been resolved.