Ipad 3 freezes, bars across screen and resets

My Ipad 3 was working as normal; I had not changed anything, or added in the last week, or even hooked up to a computer in over a week. When i was veiwing a file in 'PDF Reader Lite' a series of colored bars started flashing all over the screen, the ipad then shut down and wouldn't restart. After several minutes, I was able to restart turn on the device. When I tried to continue viewing the file, the problem happened again. after restarting the ipad, I deleted the app to try and resolve the problem. The problem came back while in another app, only this time in 'F18 Crrier Landing Lite'. But opening a music visualizer worked fine. The apps that caused problems were high in memory storage. All this happened in the span of an hour. I don't know what is going on since this never happened before. I am hopping for assistance with this problem.