I hate to tell you this but your computer is overheating. What you are seeing is artifacts caused by extreme heat. I would recommend returning the laptop to HP for service if it is still under warranty. If it is not still under warranty then you are pretty much screwed unless you want to pay HP to repair the damage which would likely be the entire motherboard if it has an intergrated graphics chip, or just the graphics card if it has one. Sorry about the bad news.
p.s. Always buy the extended warranty on laptops.