Hi Nedivah,
My game kept crashing whilst in buy mode and the things I did to rectify the problem were changing the parameters of C drive. I got this information from the technical board, subject is "Pets still crashing, nothing seems to help". Apologies, not sure how to link (I'm on my phone). Read the items that forumer MoonsAreBlue suggests.
That helped a lot. But what finally sorted it for me was another post somewhere that mentioned turning off the Internet. I haven't had a crash since I've started playing with it turned off.
Obviously your situation is different to mine but it might give you some ideas to try.