My Emachines E642 laptop gets terribly hot and sometimes shuts itself off when getting too hot, often when watching movies or online tv. I think it is a built in safery feature that the it is turned off when getting too hot. I want to remove the case so that I can check the fan because I think it is either broken or full of dust. However after removing all the screws I found the case still very difficult to remove, it was opening up a bit in a corner or so if I really made an effort and used a tool for help. But I am quite sure I would have broken it I kept trying so I gave up and put the screws back again. Any tips of what obvious beginner mistake I made trying to remove the case or any other tips of how I can check the fan and/or stopping my laptop from overheating and turning itself off?