I haven't checked if there are previous posts on this, but my Week 22 Core Duo MacBook screen flashes a lot. It changes brightness like a strobe light (quick flashes) and then I have to hit to left hinge area for it to stop. Does anyone know what this is? I don't want to have to bring it to the Geniuses, but if push comes to shove I will. Sorry if this is a repeat topic, just point me to the other one if it is.