Screen turns multi-colored with horizontal lines

Screen turns multi-colored with horizontal lines, then it either restarts by itself or its just in a black screen state. Tried changing battery, problem occured a couple of times during a 2 week period (maybe 2-3 times), then everything was fine and suddenly same thing happening, much more frequently. Figured it could be the LCD, so went ahead to change the screen as well, but same problem occuring still. Any ideas what is causing this to happen? Thank you in advance. :)