Check if your computer suits minimum systems requirements for this game:
Windows
OS - Windows XP
Processor - Windows XP - 1.4GHz, Windows Vista/W7 - 2.0GHz
Memory - Windows XP - 512MB Ram, Windows Vista/W7 - 1GB Ram
Disk space - 2GB
Video Card - 128MB
Mac
OS - OS X 10.5
Processor - Intel
Memory - 1GB of RAM
Disk space - 2GB
Video Card - NVidia Geforce 7300 GT / ATI X1600 Radeon
If all these requirements are fulfilled, try to reinstall the game.
