Sims keeps crashing...

[Seraphina90210]

So um, I got the Sims 3 a week ago and it crashes quite a lot. At first it didn't crash and I know it was because I had little things. I am not disabling custom content. Otherwise my Sims will fight more often. Because I have like eight sims lol it'll be true chaos. Okay, so before it would crash every time I save. Like 3/4 times. I'm not progressing very fast in the game. And now it's sooooooooo much worse. It just crashes randomly while I'm playing the game. And it sucks. Like the computer just shuts down and I loose everything I did up to that. So I have to do it over again. My Dad checked what was wrong with my computer and everything was okay? We even tried defragmentating the disk and lowering the graphics to the minimum. Yet it STILL crashes. Like I'm fed up and I don't know what is wrong with my game. My Dad suggested it could probably be bugs. But it might be something with the files as I researched it. If you know how to fix this, Please give me a SIMPLE and easy to understand explanation on what to do. Btw, I have Windows 7, just to be specific and make the explanations easier ^^
I'll appreciate it soooo much if you were to help me fix this.