There are two major causes of such problem and they are:
1) Your RAM(Random Access Memory) might have gone bad. In that case replacing it with working one is necessary.
2) The GPU chip might have malfunctioned and that would require a tech specialty to fix. Either reflowing it or replacing it. If the chip is not found it is time to get a new motherboard.
For the issue with your DVD, it is possibly the optic lens is failing and that means you would have to replace it or get another DVD writer.