The Sims 3 stopped working because of game save?

Hello. Recently I was start playing back my Sims 3 game after long ago, in my Windows Vista desktop with newly upgraded CPU. Before that I was played it in my Windows 7 netbook. I was playing the game with the old save transferred from the laptop. Then, it works fine for several minutes, before the game freeze and a message appeared said Sims 3 has stopped working, then, it shutting down, going back to desktop. But when I try to playing with a new game, it works fine, as long as I play it. I don't know if it was because the old save, or maybe because the compatibility. FYI, I was ever put the game mod in my old save, but it was removed a long ago, before I transferred it to my desktop computer. Also, The Sims 3 version in netbook is 1.47, while in desktop, the version is 1.57, upgraded directly after it was installed. Is there any way to fix my old save so I can play it without any problem? Thanks for everyone's help.

Sorry but I had no idea about the step 4 'Name your Potter family and save it'. I had already choosing my own Sims in my own occupied lot, but don't know what to do next. Can you explain it?

Btw, I forgot to tell you, actually, while I said my games works fine in new game, I mean the games that started from the new save. Because while I had start a new town from my old save, it stopped working too.

//EDIT

I did every single steps as you told. But stuck at the step 4 when the message Error Code 12 appeared while I was tried to save the game.