Being a PC-issue, it really can be hundreds of things. Without your rig's exact specifications, including running processes, it will be guesswork.
You can right-click the game shortcut, select properties and try running with added parametres. Like Run as Administrator. Or run in XP/SP3 mode.
You can also enter your graphics options and try altering the 3D settings. That should be pretty simple. Many older graphics card would have you select between Performance, Balance or Quality, and the game might not run without the right setting.
But I'm grasping here. Good luck.