If you're suffering from the dreaded CTD, there are things you can do to prevent it. Now this is not a cure-all fix; I can't guarantee it'll solve your woes, but it's worked for me so hopefully it'll work for you.
1. Download and install the CFF Explorer.
2. Go to C:/Program Files/Electronic Arts/The Sims 3/Game/Bin and look for a file named TS3.exe. This is the base game file however, so if you have an expansion you need to find the file for that EP instead, e.g.- for Ambitions it can be found in C:/Program Files/Electronic Arts/The Sims 3 Ambitions/Game/Bin, and it's called TS3EP02.exe.
Once you've found the file you require, first make a copy of it in case things go all tits-up, then right-click and select 'Open with CFF Explorer'.
3. Once the file is open look on the left hand side for a section called 'File Header' and click that, then click the blue box on the right where it says 'Click here', as shown in the picture:
4. Another window will open. Click in the box next to where it says 'App can handle > 2gb address space' and click 'Ok'.
5. Save your modified file and overwrite when it asks you to.
Now, this should be simple, but I encountered problems. I'm the admin of my computer, yet it wouldn't let me overwrite the file- it kept saying I didn't have permish or some shit. If you find yourself having this problem as well there is a way around it, which is to start again with the file, but before you modify it drag it out of the Sims folder to the desktop or summat, then follow steps 3-4, save it, and move it back.
And that should be it! Hopefully this will help stop your crashing issues- it's definitely worked for me. Just remember to repeat this method every time you patch your game or install an expansion pack.
Ta-rah!
