I have the SIM's software including 3 expansion packs (Living Large, House PARTY, Hot Date) When I load the program completely, it goes through all the cheesy intro stuff, then loads into the neighborhoods' screen.
No matter what I do, whether I choose to create a family or click on a house to play with, within a few moments, like 10-15 seconds the screen goes black and then it goes back to windows, like I had NEVER loaded the game.
It does not give me an error MESSAGE or any type of warning, just closes the program. I've tried restarting my computer, and having no other programs running. I don't have a clue what to do.
This is a brand new computer; I have windows XP, 1 GB of Ram, 2.39 GHz, and a Pentium 4 CPU 2.40 GHz.
This should matter but.. try changing the Mode of the game.  XP can emulate different OSs but I don't think that's the issue since sims is a fairly recent game.  A better bet is to try reinstalling the game.  It shouldn't overwrite the saved games.

I tried sims once.. I quickly realized running my own life was TOUGH enough.i've tried re-installing it about 3 times... and still the same thing happens  :-/