Hi there
A couple of things to try (although interesting that its only on one side of the TV):
- Does this happen on one or all of the connected devices (as in TV reception/DVD's/Bluray or any device) - If its only one device, try replacing HDMI cable, if its all devices, continue....
- Are you on the latest firmware?
- Have you tried turing the TV power off from the wall for a few minutes?
- Try performing a factory reset of the TV
- If all else fails, you may need to contact an authorised Sony Repair Centre : Here as it may be a hardware fault.
Cheers