Sims medieval + medieval pirates and nobles - COMPUTER SHUT DOWN

                 
I am able to download both games and install them - but when I start the game and is about to play, the computer somehow manage to shut down. 
I have experianced this a couple of times now and don't know what to do... 

can anybody help me?
I looked at the forum, but it didn't seem like anybody else has had this problem before

I really want to play this game, please help a hudge sims fan