I never ran into such a "hardware-limitation" bug, but i think its a good lesson for me
There is a way to check in runtime the hardware capability availables.

http://externalweb.exhedra.com/Direc...R_Lesson02.asp

I was told that in new directx 10 this is no longer required, coz it is mandatory that all dx10 harware videocard support all features included in the API;