Sims 3 crashing

Hello,
So I have had the sims 3 since it came out. I installed it on one laptop but it crashed about an hour in, and soon after (not because of the sims) the commuter crashed so I couldn't play again. But later when we got another computer (windows 7 acer touch screen) I installed it again. But it hardly even worked for five minutes so we supposed there was a problem with the disc. When we bought another one though, it was playable for an hour before crashing. There is no problem with space as far as I can tell or any problem with the computer being old since its very nice and only a year old. I tried disabling the DEP but it wouldn't let me. HELP?!