[Q] Phone switches on when on internet

I am using samsung galaxy note GTN7000 with CWM 10.1.3. Recently i got into a weird issue of shutdown. Phone switches off automatically after sometime when i am using internet through wifi or 3g. But if the charger is plugged in it will not shut down. Also it does not shut down if internet is not in use i.e. wifi is off and mobile data is disabled. I tried changing ROMs, went back to stock ROM but problem still persists.