Yeah, unfortunately, the problem is due to not enough RAM. While you can most likely install 4GB or more RAM in you laptop the 32-bit version of any Windows will only be limited to using around 3.2GB - 3.4GB.
Sims 3 is known for using more than 4GB of RAM especially with expansion packs. If a game need more RAM that is available through Windows then the game will crash / laptop will freeze.
The fix is to buy Windows 7 / Windows 8 / Windows 10 64-bit and ensure that the laptop has 8GB of RAM installed. You should provide the make and model # of the laptop you have so that people can very it is capable of running a 64-bit version of Windows. If not, then you will need to buy a new laptop. I would Google around to see if the Sims 3 is compatible with Win 10 if you plan on buying that operating system.