Macbook pro flashes purple and 3 beeps

My macbook is around 3-4 years old so I'm not sure if this is related to old age. Anyways, If I apply some sort of pressure on the bottom left side of my mac the screen will flash purple and freeze. The only way to stop that is restarting it which will then begin sets of 3 beeps. I've taken the bottom off, taken RAM out, put it back in, and start it back up with no problems. However, this is only a temporary fix and I have to do this at least two times a day. I ran a hardware test and it said I have no problems with my computer. I've read it might be the logistics board but I really don't know what to do. Any insight or advice would be greatly appreciated.

I need my macbook for class and I can't use it in my lap because the pressure causes it to freeze. I've previously had quite a few problems with a flashing folder (around 6-7 times) if that is somewhat related.