Sorry to bother you, but, could you please tell me this.
1.] What OS are you using?
2.] How much VGA memory are you using?
3.] What version is your VGA driver?
4.] Don't use 64-Bit CPU, please use a 32-Bit.
Notes: 64-bit has problems with drivers compatibility.
Note2: Please disable UAC control and install the game again.
This might cause the problem if you're using Vista.
Lair360, happy to help...if I can.