We need some Corona specific UV controls because the Projector shader currently isn't supported in the IR (unreliable), the Layer + Transform combo is OK but not for bump maps...
If your material projection is set to anything rather than UV-Mapping then you can change it under the "coordinates" tab - once you have the material tag selected that is. Just change the H P B values by 90 degrees, one of them will work :)
You can also place the texture into a C4D layer and then put the Transform effect on top of it. You can use that functionality to rotate the bitmap and it tends to work fine with diffuse textures... Won't work fine with bump maps though.