Sounds like you\'re another
victim of the update from Android Jelly Bean to Kit Kat, the new OS is very buggy and can cause screen lock, battery drain and a host of other weird problems. Go to Settings, More, About Device, if Android Version says 4.3, Kit Kat is
the problem. If you do NOT use ATT, you can try this link to downgrade back to Jelly Bean. If you\'re with ATT, you can either read the next paragraph, or wait for the eventual fix and just suck it up for now.http://www.androidpit.com/how-to-downgrade-galaxy-s3
Another option if you\'re an ATT customer or are little more
adventurous is to abandon
Samsung\'s version of Android (Linux) and move to CyanogenMod11. I\'ve used each version of CM since 6 and been very happy. CyanogenMod11 is just another
type of Android (Linux) and will work on the Galaxy S3/S4. It\'s pretty easy to install, just go to http://www.cyanogenmod.org/
and click on the green button.There\'s a loader you must install in Windows and a few settings to switch on the phone to allow it to install, but otherwise, it\'s pretty painless. Your phones desktop will look a little different and your phone will need to reinstall all your apps (you\'ll start all games over), but it happens automatically and all you contacts are already backed up on the Google servers.