What version (e.g. ver.20xx.x.xxx) of DirectRT do you have? You can find this information by opening DirectRT and clicking on Help > About DirectRT.

Could you please also send me a copy of your computers dxdiag file? To find it, click the Start button on your desktop, type dxdiag in the search box, and click the dixdiag.exe file. Send me a copy of the .txt file it produces.