Possible Reasons of problem
1. Lotion was just applied to hands.
2. Hands are wet.
3. Screen protector or case is preventing the screen from responding.
4. The device might have experienced some type of physical or liquid damage.
5. A third-party application is causing the screen not to respond.
1. Make sure your hands are dry and there is no lotion or any kind of cream on your hands.
2. Remove any accessories such as a case or screen protector.
3. Use dry cloth to remove any excess oils or dirt on the screen.
4. With the phone still powered on, remove the battery for 30 seconds. Put the battery in your S3 and power it on.
After doing the entire above problem is still there it means problem is caused by some installed application. Keep an eye on which application you use before the problem starts. You will have to uninstalled application which is causing it.