Try this :
1. Click Start, click Run, type dxdiag in the Open box, and then click OK.
2. In the DirectX Diagnostic dialog box, click the Display or Display 1 tab.
3. In the Device pane, note the value that is next to Approx. Total Memory, and then click Exit.
4. If you have less than 16 megabytes (MB) of video memory installed on your video adapter, install additional video memory on your video adapter, or install a video adapter that has more video memory.
You also could try updateing your video cards drivers.....
Tony