Same problem here. You are not alone, tifaia! Although I can sometimes go for a while before this happens, this soft crash can occur randomly during gameplay, or while saving, which corrupts the saved game and necessitates reverting to a backup saved game, as I mentioned in another post. It is super annoying either way.
I will try the following and report back if it happens again:
*Update DirectX by locating the DirectX End User Web Installer at Microsoft.
*Update .NET Framework 3.5
*Update C++ End User Runtime
I have tried the obvious - ran defrag, checked/repaired disk errors, virus scanned, disabled startup items, made sure only basic Windows services were running in background, uninstalled virus scanning program, blah blah, ad nauseum. Nothing helped. System is hand-made by me. Have not experienced problems like this with a game before on this machine. Video card has been upgraded since then. However, good to note that Sims 3 did this before and after the video card upgrade. I didn't upgrade the video card for performance, but rather because I prefer ATI GPUs over Nvidia. So no, I wasn't having graphics card issues.
Operating System: Windows Vista™ Ultimate (6.0, Build 6001) Service Pack 1 (6001.vistasp1_gdr.090302-1506)
Language: English (Regional Setting: English)
System Manufacturer: NVIDIA
System Model: 132-CK-NF79
BIOS: Phoenix - AwardBIOS v6.00PG
Processor: Intel(R) Core(TM)2 Duo CPU E8500 @ 3.16GHz (2 CPUs), ~3.2GHz
Memory: 8190MB RAM
Page File: 3423MB used, 13165MB available
Windows Dir: C:\Windows
DirectX Version: DirectX 10
DX Setup Parameters: Not found
DxDiag Version: 6.00.6001.18000 32bit Unicode
---------------
Display Devices
---------------
Card name: ATI Radeon HD 4870 X2
Manufacturer: ATI Technologies Inc.
Chip type: ATI Radeon Graphics Processor (0x9441)
DAC type: Internal DAC(400MHz)
Device Key: Enum\PCI\VEN_1002&DEV_9441&SUBSYS_E89A174B&REV_00
Display Memory: 3827 MB
Dedicated Memory: 1015 MB
Shared Memory: 2811 MB