Hmm, without going back and looking at how the stages were done, but are you saying you wern't passing a bmap_to_uv()'d bmap in the other shaders? From my test (ill have to dig up the thread), it looked like bmap_to_uv() changes the texture format to D3DFMT_V8U8. I'm wondering if there are cases where ATI will happily use other formats, and nVidia cards are stricter.