HP Envy laptop supposedly overheating

I have an HP Envy M6-1184CA that I got just a little over a year ago and it was working perfectly, until up about a month ago, when it just randomly started to do 'thermal shutdowns' when I play my games. It normally does get hot when I play games, and can easily reach 65-72 degrees Celsius when I play my games. I use a cooling pad and I remove the battery when I play the games. For the months that I had it where it wouldn't shut down, it would reach those temperatures and it would be perfectly fine. It wouldn't bother me about anything. Now, about a month ago, it started this problem for no reason. The temperatures could actually be LOWER (60 degrees) and it'll do a thermal shutdown which is extremely annoying because a game can be loading and not making the laptop generate a lot of heat and it'll do a thermal shutdown. Sometimes it'll hibernate, but most of the time it just turns off very suddenly. I know for a fact that it isn't overheating, as it has been much hotter in the past and it didn't do anything unusual. I know the heat can damage the system, and when it finally craps out, I'll get a desktop system, but that shouldn't be happening now. I did take off the keyboard and removed the CD drive to blow compressed air inside, but that hasn't helped. I have the laptop sitting on a dual-fan cooling pad made out of some kind of metal to draw away heat and the fan vents on the laptop are completely unblocked. As far as I know, there is no dust inside the machine. When I went to blow compressed air into the laptop, I tried to take it apart, but the instructions I followed were extremely unclear and I could only get as far as taking out the optical drive and removing the keyboard. Any advice would be greatly appreciated.