directX error resolution??

Core-i5 2430M ,6gb RAM ,2 gb nvidia gt540m

It crashes few minutes after starting the game with the following error:

"DirectX function "device-->CreateBuffer(&dxDesc,0,&buffer... failed with E_OUTOFMEMORY

('Direct3D could not allocate sufficient memory to complete the call)"

Any solution guys??

I've not seen that problem but would go down the route of usual suspects:

Update to the latest drivers for your graphics card

Download / re-install the latest version of DirectX