If I had to guess what's wrong with your laptop I'd probably guess a) it's overheating because it has ventilation issues or b) you have faulty memory.
Turn it of more often to see if that alleviates the problem and make sure that you don't have dust covering your laptop's vents. You can also test for faulty by running
memtest86 (memory test application). You probably want to create a bootable memtest86 CD from the
ISO.