Sims 3 makes my laptop crash?

I have had the Sims 3 game for a while and use to be able to play it on my laptop but I haven't played it for a few months and just started playing it again, but now each time I play it after about 15-30 minutes my laptop will completely crash. This never used to happen. I've been told it's probably overheating or there's dust in the fan. How can I fix this problem? Will a cooling mat help if it is overheating?